A properly done 7m will be fine for what you want, but I'd suggest MHG, ARP head studs, ARP rod bolts, and doing some cooling/oiling system mods. aluminum radiator would help. extending the oil pickup tube closer to the bottom of the pan, adding baffles to the pan, and a full flow oil cooling system. the stock cooler will NOT be sufficient for drifting.
1JZ/2JZ would be great platforms as well. Look at terbo_boost on the forum, he's sliding a MK3 with 1JZ and seems to do pretty well with it. Ahmedootie I believe is putting a 1JZ into his BMW as well haha.
Pretty much any V8 would be good too. Either worked over 1UZ if you have the know-how, or an American motor which is cheap/easy to come by/cheap as hell to build up. If you want to turbo it, I'd say 7M/1J/2J as parts for those are readily available. V8 turbo swap a custom manifold would have to be made, lots of headaches involved.
Hope this helps at least a little bit