Your engine choice is delightful .... looks like a miniature Franklin 2A-120 (O-120) Twin..... Guess they do not make miniature O-320 clones....

Wonderful project

some additional thoughts.... if that hinge is to be laid on top of other joints that have already been silver soldered then you will have precluded Tig Welding on that spot... as you will draw out the solder from the previously soldered ones.... you could however solder them using jewelry practice of using the next softer grade of silver solder

Hard
Medium
Soft

each softer grade melts at a lower temp allowing you to layer several items in steps without damaging the one done before....

please keep us posted... if you like PM me and I can probably help you with some sources....

for hard solders... this stuff is 80percent silver...

http://www.riogrande.com/Product/Sil...d/101730?pos=6

These guys at Rio have more hard solder options... plus their site is fun to look through...

http://www.riogrande.com/Search/hard-solder