[Will a 518 bolt up to a 360 or will I need an adapter plate?
They came stock in trucks with smallblocks so its a bolt in for you. I had to switch to a bolt on bellhousing to adapt to big block.
I called around here to local junk yards to me and requested a rebuildable core , found a518rh which used a kickdown like 727 (hydraulic governor)and with a kit from PATC has a couple of switches to kick in the overdrive automatically without a computer. I bought a core for $200 , plus upgrades to the planetarys and good red alto clutches ,shift kit ,etc. A plus to the 518 it has a better .69 overdrive compared to the gearvendors. I wont have near what a gearvendor would cost, if I wanted something that would hold more power than a 518 I would go to a 4l80e gm tranny with a conversion bellhousing which is basically as stout as a turbo 400 ,this would be the tranny for 1K type power,with upgrades of course