Hi Joe,
Wait until the models start reproducing if you think things are expensive now!!!
If the hardwood rails are too wide apart for your motor cut two strips of alloy to lenghth the correct width for your motors mounting beams. Bolt the alloy strips in place onto the hardwood rails with countersunk bolt heads or bolt at the extreme ends of firewall and front of the rail.
You can still slide your motor backwards and forward for balance and bolt it in place to the alloy rather than the engine bearer.
Cheers,
Colin