It appears to me, with the number of time you have created posts identical to this, you are unsure of what to do, not that experienced in fish keeping or dont like the advice youve been given so far! Thats ok, what is this forum for! So down to business the guppies sound like a good idea but beware because they will mate! You can sell these off to an lfs tho. Id recommend 3 khulis as whilst that is pushing it slightly if they are the only bottom feeding fish it should be fine. 2 dwarf gouramis or red honey gouramis would also be good and then theres golden barbs, cherry barbs, neon tetras, cardinal tetras, black widow tetras, bleeding heart tetras, black phantom tetras, x-ray tetras, lemon tetras.....! U get my point, these are all shoaling fish and so any of these in a shoal would do well in a 70litre.
Any other questions?