If the track has smaller jumps, or races 1/10th and 1/8th on the same small jump style track the XB8 should do excellent. On rough blown out tracks with huge jumps it'll be hurting.
Amain still has parts. I'd use the Xray clutch bell and any shoes/springs you want.
I'd put in the OS 21XZ-b, P3 plug. I have the hardest time tuning engines tht don't have a turbo plug.