Yes it is. The 600ho is the same bottom end as the older 700.
U need the 01 and up jugs with the bigger bolts ( size of holes ) and if I recall a 670 ho piston... U have to either cut Ur 600ho head to match or a 700 head.
Did it to my 04 600ho. Pulled better than a 800ho ( even a modded one )
Real snappy power too.
Think it was 138 ish hp and 112 ftlb.
Call al at the sled shed in Revy. He has done lots.