Could this idea work ? Did other guys did this ? 318 infos

I have never used a 2-4 adapter. I would consider the “plenum” volume on that cast 4b intake and the lack of fuel feeding it.
I know it will run but it will probably bog.
If it runs right now I would experiment….since youre budget building I would install the 360 2 bl cam in no matter what! throw the 318 2 bl back on and the Carter.
Or… try your 340 4b intake with your 2 b adaptor and Holley.
Watch those holley 360/400 2 bls, the throtte body screws loosen themselves and you end up with a soggy carb. soak the carb in fuel to get the gaskets soaked then snug them up very little if needed.
Better to have a small leak on the carb than to have stripped one of the base screws( if it isnt already stripped from someone already over tightening). Common! They strip easily.
I put a 360 2 bl factory cam in a 78 318 with untouched 318 heads and a 360 2 bl truck intake and holley 2bl. It worked great and I noticed quite a difference without mods.
If you know how to work with carbs a used TQ can be your new favourite friend and will definitely still work with your 360 2 bl cam with minor adjustments.
Swap meets, moparfest, cruise nights, or someone in or near Montreal must have a used 4 bl for you for reasonable $!
Since you have the 2 b parts, try them in the meantime.
360 2 cam first if thats the best cam you have, It works if you dont dump too much fuel on it.