I am developing a deep affection for JB weld. It is holding an a side plate for Herbs 9N radiator. So I did the same for my 77 Dodge camper van. It just survived a trip to the Arctic. 550 miles, one way of the worst gravel road. 2 days before we left, while checking the E fitting on the fuel gauge tank sender unit. It broke off, revealing a 5/16 hole, where the gas pored out. I put in a 5/16 bolt with rubber O rings, and covered with JB weld. That too survived the trip. Gave my JB weld to a trucker who had a cracked fuel pump. No results to report. Bought a new supply when I could.
YAMV Island Mike Researching HP options for the mighty 318

HP Options for the 318?
That would be a 440 with either the rottenchester carb instead of the thermoclap or perhaps into an Edelbrock/Cater AFB Wanna be.
Now if your running that Torqueflight 727 Trans, those are a very "difficult" unit to rebuild. It takes two "C" clamps and a 18" #2 Straight blade screwdriver along with a few sockets, a ratchet and maybe an extension.

If your insistent on staying with the 318, you might look into Edelbrock performance packages. Twisted valve heads might also be a consideration but the factor then becomes one of how much performance increase will you see from the Eldelbrock head to the twisted valve heads once your already changing things. Another option is the roller cam with roller hydraulic lifters and gapless rings.
How deep are your pockets?
If you desire to save a buck or two and let someone else do the design, Edelbrock perf packages are worth a look, but there are always a way to make those better also.
Polishing alum head ports is not advised but gasket matching is.
Rottenchester 4 BBL carb is a direct bolt on replacement for the Chyslur Thermoclap.
Same spread bore bolt pattern, no adapter.

Have fun!