Top end rebuild questions for a '67 225 V6

I did a complete engine rebuild about 15 years ago, but didn't replace my cam, timing chain or cam bearings. Now at long last, in spite of above average tuning and attention to detail in the process, I get carburetor back fire at higher RPMs and I'm convinced I need to re-do my top end. I"m thinking new cam, lifters, cam bushings (because I've never had particularly good oil pressure in spite of an oil pump re-build some years back), valve springs, timing chain/gears, etc. I have questions. I've tried searching and have checked the forum back several months, but haven't found the answers to my questions. It's probably back there if you look hard enough, but I couldn't find it. Hope you guys can help me out:

1. If I pull the cam and replace the cam bushings do I have to pull the engine? Just pulling the front clip is a whole heck of a lot easier. I checked the Hayne's manual and they say pull the engine, then remove the cam from the front (huh?) That's no help. Is there a reason that I have to pull the engine to pull the cam? Do I need that kind of access to the rear of the engine block?

2. If I do the replacements that I mention above, should I consider replacing my rocker assemblies? Is there some clearance that I can check to determine if that's necessary? If I replace valve springs should I also replace rocker assemblies? Anything else I should think about here?

3. I thought I'd cut a notch with a hack saw in the cam bushings to create enough clearance to remove them. Then put the new ones in the freezer before I slid them into place. I've never replaced cam bushings. Is there a better method to do this? Is this perhaps why I might consider pulling the engine... so I can more easily access the rear bushing?

That's all I can think of for today. Really appreciate any wisdom you all can pass my way.

 

Usually you let a shop do the cam bearings. They'll want a bare block. To do it yourself, you'll need a cam bearing installation tool that fits your engine. The tool is a long shaft with bushings that drives the cam bearings in and keep them in parallel. You cannot drive them in without the special tool. Look on the net for "V8 cam bearing installation" - there are YouTube videos that show how its done.

The tool for a Chevy is not too expensive, but you may need the (expensive) universal installation tool for a Buick.

I would not trust a Haynes or Chilton's manual. The Jeep factory manual is reasonably priced.

 

As Timgr says.
The bearings need to be perfectly aligned as a set, and I think the tool needs to have clearance at the rear of the block as well as at the front.

Ditto on the manuals, too.

 

Engine must be removed to remove the cam bearings. Especially the rear one. They get pushed towards the rear of the block as they are removed. You say you did a complete rebuild but didn't replace these? Standard replacement during an overhaul. You can't split them with a hacksaw. For one thing you'll fill the engine up with filings. For another you can't get a hacksaw in there.
As said above, installing cam bearings can be tricky even with the correct tool. They are very easily damaged and must be aligned correctly.

 

Everything that has been mentioned above and more..........................You mentioned valve springs , If you never had the valves ground in that length of time more than likely the backfiring is due to valve leakage at the seat in your heads..........Since the motor has to come out anyway you may as well freshen up the bottom end also........sounds like a complete rebuild to me.
And look your oil pump cavity over...........If the end bore and cavity walls are scored even with new gears you will never have good oil pressure.......there is a kit out there ( I think Milan was making them )that uses V8 gears which are a 1/4" taller and should increase volume and perhaps oil pressure subject to the gear cavity...........rocker tips and rocker shafts need to be inspected or rebuilt. Once motor is disassembled follow the path of the oil galleys from the pump and root out with small brushes especially the feed that comes up through the block and cylinder heads to the rockers.......any debris in there and your overhead will suffer.

 

+1.. Can't do cam bearings with the engine in the Jeep. You also need the installation/removal tool. There's no way around that. You'll likely be much better off having a machine shop take care of that for you. Might as well do the bottom end too while you have it out and apart...