Choppy idle cams are soooo obsolete. The sound of the 1960’s never produced all that much power against the cubic inches. Much was made of getting 370 SAE gross horsepower from the LT-1 350 with 11 to 1 compression. So rather than refining the engine they turned to a cam that barely closed the valves 312 degrees total duration with only .458/.485 inch lift and 242/254 duration at .050 lift. These needed 100 plus octane fuel and a 750CFM to reach 370 Hp. Plus vehicles like this only came with manual 3 or 4 speed transmissions and rear gear ratios started at about 3.5 and went up from there 3.89 and 4.11 being common. Try spending a day listening to your engine spinning at freeway speeds. Automatic transmissions behind performance engines were something occasionally seen as experiments at the race track, not available from the OEMs behind performance engines.
Today the emphisis to make power is preserving compression pressure on less compression ratio since hundred octane plus fuel is not at the corner gas station. So combustion chsmber design has changed a lot to increase the efficiency of the burn. For Chevrolet these Ricardo (heart shaped) chambered heads first show on the 1992 LT1 and the 1996 LT4 in aluminum and iron for the 94 L99 Gen II engines. The 1996 L31 Vortec introduced this chamber to pickups with conventional block first then heads cooling. The LT1, LT4 and L99 are reverse cooled which routes coolant to the head first and returns from the block. Gen II blocks, heads, intakes, ignition, coolant pump are not interchangeable with the Gen 1 engines with the exception of the aluminum heads can be modified back to conventional coolant routing with some welding, remachining and creative external coolant returns.
The aftermarket industry has picked up on the ideas of the Ricardo chamber and manufacture heads from moderately priced imports to very expensive domestics that blow away anything from the 1960’s using much less can duration and lower compression ratios suitable for 89/91 octane E10 unleaded at the corner station. A cam timing like the Comp XE268H with 268/280 overall degrees having 224/230 at .050 and .477/.480 lift through a 1.5 rocker at the valve will easily produce 390 SAE gross crankshaft power using L31 heads and a 650 CFM carb. With a 750 CFM carb and attention to valve train details its almost impossible not to get 420hp from a 350 all on 9.5 to 1 compression. This makes a lot of torque and power under 6000 RPM that is very automatic transmission friendly and does not need a high stall converter, higher than your 1400 but nothing crazy getting into 1700-1800 stall is sufficient. The exhaust note on this cam rumbles but is pretty smooth at idle but in an engine built to todays knowledge base when it comes on it is gang busters to use the old phrase.
If you’re not building like this as I outline above but rather for rumbly idle exhaust sound you will spend a lot of time looking at the other guy’s tail lights. So you need to get out of this 1960’s think and get modern. In the words from my teen years “you gotta get hep man”.
Like I’ve said the devil is in the details, for all the words I’ve used this is still like skipping stones across the pond. Since this an early build for your history you need to talk to us before tearing into things and buying parts. You need to start with a realistic power goal and realize that changes in engine power are sooner or later effect the driveline and chassis. The first issue is getting the power the next is component survival further down the line. Big power numbers especially in terms of torque will make you learn transmissions, driveline and rear axle technology very quickly soon followed by concepts of the suspension, frame and body. You will find that big power numbers have to be controlled or you crash, I’m wishing you discover the former before suffering the latter.