it'll be safe on the mk2 top mounts, just the mk3 gti ones are a bit better as they're stronger. the early mk3 non-gtis had mk2 top mounts on em anyway. if you put brand new top mounts on before you swap it over it will be fine

if you want to put the mk3 gti top mounts on, you'll need the MK3 GTI threaded bushes and early upper spring plates, plus obviously the top mounts + bearings. do a search in the vw parts section of ebay for 'lemforder' thats an oem supplier for VW and do the best quality top mounts & bushes. usually theres a seller doing lemforder mk3 gti top mounts & bearings for a good price.
1H0 412 341 - MK3 GTI upper spring plate, small size
1H0 412 365 A - threaded bush