I know the 911 Speedster you're talking about, I remember it having American Racing wheels. Have a photo of it one of my Porsche books just haven't been able to find which book!
Edit - Found it!
Thanks Trevor. Having the engine position locked in allows me to confirm clearance now. Had to adjust some things but happy with this. Fabricated a simple rear firewall which is not provided in the kit.
Had to shim out the front hubs to get proper track width and accept the fat racing rubber. Fabricated simple rear hubs to accept the aftermarket wheels.
The scribing helps the seat detail significantly and is well worth the effort - free detail. Work like this can easily be overlooked by those viewing the finished build assuming it was cast that way.