OK thanks for all the replies, AVS2 650 is looking like a good choice but will it work with the square bore manifold I have? View attachment 1716171154
I am going to open the up the center section and port the manifold as per Gary Pavlovich's advice but that might not be for some time.
The Edelbrock carbs have a dual bolt pattern, so should ba a dropon that way. The AVS2 650 should be a bolt on. The AVS2 800 likely requires opening the secondary bores in the manifold.
A young lady that lives here has a poly engine with a 6 pac her Dad built. Otherwise it is stock.