Mean 318...or stroker....hmmm

Yes, except that small notch on eh LA block. That bore notching is pretty minimal and extend down into the bore about as far as you see on the bottom of the bore. You can do it with a Dremel (or maybe even a rat-tail file LOL).

On the stoker kit, 390 is darned close to 408 or 416. But if you have to bore a block, then getting a 360 block might make sense. I personally would not sweat a lot over it for the use you state. You're gonna be roasting tires either way!

On the stroker, you need to look into internal balance or external balance, especially with the lower cost cast crank. You ought to be looking at a new damper anyway, so you can get either that you need. If you go with the kit as-is, then I am pretty sure you are looking at finding having it balanced locally. If you go internal balanced, then you can stick with what I assume is the neutral balanced flywheel that you possess. (What did that flywheel come out of, or do you already know it is neutral balanced?) SCAT can internal balance for you, but it is a higher kit price IIRC . So account for balance work somewhere in the costs; the cost differential just got larger again.

IMHO, at 350-375-400 HP, studs on the mains are not mandatory.

Upgrades to induction and heads can always come later. You already have 360 heads so that helps.

BTW, quench on the milled 360 heads (which still retain a shallow open area) is not going to happen with the standard pistons in the SCAT kits. There is no piston with a quench pad on top for the 318 (that I am aware of), like for the 340 or 360. To do that, with his present heads, the OP would need to go to a larger bore block. Quench is desirable for 2-3reasons, but not mandatory; IMHO, if your static CR is down in the 9.5 range, you'll be able to tune it up for pump fuel OK.

Since you cannot get quench here with these heads and no quench pad available on the 318 pistons, then zero-decking does not get you anywhere.