I found these on ebay, took a chance and they work on a pierbon tt2 frame
The ebay seller is forza moto in France
Paul

Hey Paul, glad you brought this up. I use to use F1 engine bolts and they are no longer available. I found that the early 90's 900SS rear engine bolt works just fine. Paul, the bolts look like they are tapered from 10mm to a larger size? Do you drill out the frame boss on one side? I think with the Nichols bolts they need to be drilled out. Lou

Lou, the pierbon frame is threaded at both front and rear mounts, a regular motor mount bolt will fit but you can't get a socket on it!
These have a nice tapered head with an 8 mm hex!
They were listed on eBay at 916 racing or 996rs.
The seller has a few left.
Paul

Hi Paul, most every 'new' frame, and by new I mean never bolted to a motor seems to have the right front boss threaded. I have always assumed it was more a by product of how the frame get's 'jigged' when it's welded. Because most TT's I've seen have two separate front motor bolts with no threads on the frame bosses just the cases. I've always drilled the boss out to install the right front motor bolt. I've always wondered if it makes a difference from a handling or rigidity stand point to use a single bolt or two separate bolts. I have had some of the single long bolts break over the years but never a front. Those bolts you have mentioned look really interesting. Also the bolts I use front and rear are socket head Allen bolts. Since you have a Moretti I am sure you couldn't get a regular socket to take out the hex head suspension rocker bolt from the frame. I machined down a socket for it to fit. I now have a 'special' Moretti tool. Thanks, Lou