318 build for light weight BCuda 4 speed car

I have couple 360s but they are external balance which would mean me flywheel clutch bellhousing zbar clutch fork and my custom headers would then need redone as they tuck tight to the floor and bellhousing. So to go to the larger bellhousing for the external balanced flywheel for a 360 would be rather costly and lot more work. I'd be better off with a stroker cost wise. I dont see 18 ci less than a 340 and a bore .06 smaller than a 360 not capable of making power with head cam and compression. Plus I got this 318 machined block and 360 heads and all machined and ready for couple hundred bucks. I want to see what it will do as everyone building 318s is always a budget deal or a daily driver and most all are auto trans.

Eventually my 72 360 block will make its way in but not for awhile
A larger bellhousing for an externally balanced 360 flywheel? Because something is balanced different it needs a bigger bellhousing?..