Those brackets for the jackshaft and the quality type bearings look great! The engine nicely degreased and on a perfectly clean baking tray wow too.
Yep, the angle bracket way is good and I added a few more attachment points as I intent hard use.
The angle brackets for a engine platform I did as an earlier build I did where my dad helped and braised the platform to the tubes. There was a slot for the bolts not holes. That allowed moving engine forward and aft to adjust tension on a belt drive without any clutch.
The picture shown attached, yet at night and not too clear is the current one welded that I did. I added more to the bottom of the platform to add strength. The parts attached to the top and lower bars was to help avoid all the stress cracking the bottom tube by spreading out the weight.
I do the no pedal dirt bike riding and it is hard on the frame. Gotta be over 40 years ago had the frame crack right there. Numb skull as a teenager, I continued to ride it with about and inch gap in the tubing till my dad had time to get it to the shop. Now I have my own MIG so no more of that.
MT