The bore casting is slightly thicker on the f10a I think so it might not be possible to bore an F8a block out enough?
As for the other parts it should be simple. You would just need the 410 crank and pistons fitted to get to 970cc.
Some info for you

As you can see the only difference in the cranks is the stroke so they can be swapped, the extra capacity is also made up with the piston compression height, I haven't found the conrod lengths yet but the F8a and F10a use the same conrods.
Sj410 con rod 12160-73001
Lj80 con rod 12160-73000
