long time ago I used pc2amiga for transfer, its very fast but requires KS2.0+ . If all you have is 1MbA500 KS1.3 you could use softkick to get KS2.0 (presumably you somehow got legal kickrom), then you're left with 512Kb free RAM. its almost enough for undms+pc2amiga. don't know about 'unADF' but it should work.
of course, best solution is to get some 'bigger' Amiga..
don't forget to cover the HD hole and don't save valuable data to HD diskette
