6-Pacs are nice and all, but;
IMO, your engine wants a DP carb, or a TQ set-up
The DP will let you open the secondaries any time, instantly, to deliver all those 436 ftlbs to instantly to annihilate those 255s at any speed up to....say 50 mph, or more.
The TQ would be only slightly slower, but offers better response on the primaries, and the possibility of much better fuel-economy on the hiway.Unfortunately,tuning kits for it are NLA, so sometimes you have to get creative.
That 600 will be fine most of the time.
The 6-pac can be made to perform, but it's a lot of work. But they sure look nice.
That MRL engine will want a minimum of 700cfm; my 360 didn't wake up until I put a 750 on it. I'm pretty sure it could use still more.
Another thing is the manifolds under those carbs. Many tests have shown that the 6-pac manifold leaves a lot of power under the table.
And tests have shown the AG to be an excellent all round performer, and it does seem to keep the carb cooler. I have no issues with boiling fuel, on my 750DP/AG.
And I run no regulator on my P4007040 pump.
I too run a 3/8 line, but it is 1-piece from pump to dual-feed.
Contrary to convention, I run a large-canister EFI filter back at the tank, and the pump has no problem sucking thru it. BTW it's been on there since 99 and has over 125,000 miles on it; so Ima thinking of replacing it.
Oh yeah; that flywheel in post #33 does not look at all like mine; a 1971 360LA; the balance holes are all different.I'm not saying it is wrong, just that it looks wrong.