[lust4speed]

Lots of great first-hand information. Sure looks like the 3.73 ratio will work just fine for me.

Did I mention that Strange has their Black Friday sale on all their rear ends and accessories with 10% off the entire order and free shipping? Sale is on until midnight Monday, 12-2-19. I won't be able to afford any more good deals for a long time after the trans and rear end.

[Formula8]

3.73 and TKO600 here. With my 455 and SFT cam, for a street car obviously first gear was a lot but I rarely do hard clutch drops from a "dig" anyway and it was a perfect combination in my view as I could lug down in 5th without an issue. That combo would get 11.5-12" of vacuum and idle pretty easily at 750 rpm.

Now with the 433 and roller cam, it has not been as happy with the 4th to 5th thing as PDC describes. I have some tuning issues to work through now that I am at 10.5-11" of vacuum. I think the springs in my distributor are too light for 1500 RPM and the timing might be bouncing around which may be contributing but over the winter, I am converting the car to FI and timing control so we'll see.

Either way the 3.73 combination is going to be pretty hard to beat and I don't think I would go with much less than that.

[Formulajones]

I'm betting the fuel injection and timing control change will cure all your woes with that deal. Most of it is self tuning and precise control will make things happy in a much shorter time.

Takes quite a long time of driving and trial/error to dial in a carb and distributor as well as a vacuum advance, and find what makes the engine happy in all scenarios when you're trying to lug an engine around in overdrive that has a rather large overlap camshaft. Especially a small cube engine. Eventually though it can be done.

Since you're planning the swap, it's not worth the time and effort to fiddle with what you have now.