[Fot] TR-4 front sealing block screw / bolts?

[Tony Drews]

Anyone have a few extra TR-4 engine front sealing block screws / bolts?  
They are a weird 5/16 course slotted head bolt.  I should have gobs of 
them but don't.  Moss doesn't sell them, and the screw slots are getting 
buggered up in mine.

#43 in this exploded diagram...

https://mossmotors.com/tri-001-external-engine

Looking for a source for good used or new ones.

Regards, Tony Drews