There is a stepped cam on the Q-Jet too. But as you found out, it doesn’t pull itself to the next step as it warms up, you must blip the throttle as you did.
I think you will find that the most you can safely go on backspacing is 4 1/2” To 4 3/4”. Otherwise you will run into the tie rods. The larger wheel diameter you stated may give you an added advantage. Compare your current wheel to the tie rod, then measure your backspacing.
Glad your issue was simply resolved. The Quadrajet really is a good carb. I have restored and run many. Cliff Ruggles has a great book on how to rebuild and modify them. Highly recommended read. Click on the below link.
https://cliffshighperformance.com/
The key is to match the sensors to your gauges, or warning lights. Use the senders your truck calls for. It doesn't matter what the engine is. It is the signal the senders give to the factory gauges. Sometimes you must adapt the correct senders to the donor engine.
Flow chart. 12V constant at distributor (while cranking too), hot wire plugged into + battery terminal, coil grounded, coil carbon button installed, control module plugged in at both ends. Best wishes
Should be a fun build. Oval port heads, dual plane intake, 9.5 compression, headers, and a healthy hydraulic flat tappet cam. Sexy and affordable. Would recommend ARP rod bolt when you get the connecting rods resized. Grrrr
Yes you can use the 350 mounts. But if there is a plate between the mount on the block, use that too! This is needed for proper spacing with the frame mounts.
I leave the transmission in place.
I converted over to the factory shroud
I vote 275/60R15 on all four corners all day long. Fatter looks better, and the 8" wheel is perfect for this size. White letter out only if BF Goodrich. Classic. My 2 cents worth.
I want to bring attention to a steering gear rebuilder that does impeccable work. Redhead Steering Gears. I have used them many times in the industry I am in. I have always been impressed. Clink on the link below.
RedHead Steering Gears - Manual & Power Steering Gear Box
Consider a 383 crate engine from GM Performance. You will appreciate the extra torque of the longer stroke engine.
https://www.chevrolet.com/performance-parts/crate-engines