The front wedge of a GPR is; 1.32", 0.36" wide, 0.12" thick.. (according to Track of the Wolf)
The rear wedge of a GPR is; 1.35", 0.36" wide, 0.12" thick....(according to Track of the Wolf)
I would suggest trying it, and if needed you could always file it...
However, contacting Lyman with your question would be your best bet, IMHO... - and they probably have what you need...