The main problem is the lowered die of the fc-pga chips. Check your heatsink if it covers the side of the plastic socket that bulges out (the side that has the word "Socket 370" if the heatsink covers that part of the motherboard/adapter card then you'll have a tilted heatsink on the chip. The newer heatsinks will have a groove cut into the chip to make it fit correctly. On the older heatsinks, if you use a grinder or if you can file down that edge of the heatsink it will fit properly on your fcpga...
I'd just go cheap and go Gorb, or for a few bucks more Globalwin FOP/FOB they'll do the job well too...