Welcome, Takhli!
If no one has the parts, you might consider a vacuform canopy. Here's a link to Sqaudron's set for the A-20G:
www.squadron.com/.../sq9550.htm
I have the AMT A-20 kits, for conversion into the P-70. I'm trying to remember, but I think some P-70's were A-20A's, while the later marks were equivalent to the -G. I have the Squadron "In Action" book, I'll have to look it up to confirm.
I second Eric, too, you might want to post this in the Aircraft subforum (or just ask the moderators, like Tim, to move the post for you), it might get more visibility there.
Again, welcome to the forum, welcome back to the hobby, and I look forward to seeing your P-70 build!
Brad