For writing a real classic amiga game I'd be tempted to use devpac to write 68000 assembly.
Speaking of which, I've got an immaculate boxed copy of Devpac 3 with manuals and original disks for sale if anyone is interested?
Also have AMOS Pro with disks and manuals in same condition for sale too.
Might have BlitzBasic 2 as well but will have to check when I get home tonight.