Motor value

I found two PCR 100cc vintage racing motors. One is new in box. Comes with pipe and the other is just the motor but no carb or header. They are asking $600 for both. The motors are spotless. I considered restoring a vintage 1960's kart in the future. Would this be a good choice of motor and is it at a decent price?
IMO that's top dollar. I'd try a lower offer. And just my opinion but they are more of a fit for what I call a classic kart ....around 1980 give or take .
PCR's are not 60's era. You'd need an 80's+ kart to be period correct with a PCR. Not a bad price for the engines tho if they're in decent shape. I'm currently rebuilding a pair of 321 Jacobsens to put on a '61 Midwest Trackmaster that will be arriving next week. But also remember, not knowing the condition of the frame, not all have the structural integrity now that they had in the '60's when new. Well tuned PCR's may just exceed it's capabilities. JMHO -Alan-