New project 1957 3600 NAPCO- NV4500 swap questions

[WIDESIDE72]

I am normally on the 67-72 section, as i have restored a 71 gmc C10 swb stepside and 72 chevy C10 swb stepside and currently own a 70 c20 i am swapping onto a swb chassis with an LS1/ 4L60e. (I have also owned a 55 3100 big window for 35 years (since i was 14 yo!) Last summer I stumbled across this 57 3600 NAPCO. It was missing the engine and transmission. A previous owner installed Motor mounts for “modern” side mounts. Since it is missing the engine and trans, i am contemplating installing a stock 97 Vortec 350 with a carb intake that i have in storage, along with a 1993 NV4500 trans. I Had a 1993 GMC K2500 a few years back and was impressed with this trans. I dont have a bellhousing, And the original setup for an NV4500 ised a hydraulic Clutch with the slave on the passenger side. I was looking into an oem (cheap) bellhousing to use, but the trans mounting pattern is different on those (SM420/465). So far the only option is a bellhousing from Advance Adapters (~$450) Any ideas? I suppose i could buy An oem bell and have it drilled, or drill it myself, but due to their not being any machine shops close to me, that is a hassle and i am not too confident in modding one myself.