I just bought a very used Great Planes Big Stik.When I checked the firewall to thrust washer distance it is 4 inches. All the old specs I can find say 4 1/4" to 4 3/4". Which is correct and does it make any difference as long as the CG is in the right range?I don't want any surprises on the maiden flight.Also the motor mount is one that has two metal straps to hold in the engine. Specs say 0 degree down and side thrust and this what will be used. I soloed on a Sweet Stick back in 1978 and want to try again.I recovered the plane and fixed some hidden flaws but the motor distance has me worried. Thanks.