gussets

Just a pet project I'm working on. Trying to track down when the reinforcing gussets existed (behind the left rear cylinder stud). This chart shows what I've been able to determine so far. XS1/XS1B engine case revisions by serial number 1970 XS1 S650- 000101 - Rev-0 case, no reinforcing...

Here is an odd ball frame I picked up. I have plans for the swing arm, but I am thinking of using the rest for brat style some thing or other. The head tube is not xs so is a little hurdle. The question is will my engine cases be ripped apart in no time? The downtube is cut off below the...