I've very much considered it but I figured the WESSEX R69SP was close enough for now.
I think when it comes to pure pace it's impossible for the GT40 to compete with the 917K. The GT40 dominated in the reliability and the ability to quickly change the wear compenents. Neither of those points matter in LFS unfortunately.
I the short form racing we generally see in LFS the 917k is just too fast, as you can see if you run the WESSEX R69SP VS my GT4D.
I may still consider modeling an actual 917K but I have probably 8 or so mods I'm finishing and polishing now.