Hi BSA Dave. Yes you made a decent job of your Banda. I have built 2 x Honda engined bantams  both early D1 s, 

1, with a cg engine the other with a Honda 125 tde twin,( now that was a job and a half) . am lucky as i have a MIG welder  so fabricating is a lot easier, 

I only used  the Honda engine as i wanted all the rest of the bike D1 plunger , wheels, forks etc all D1, even the chain pitch fits both sprockets.  

The engine in the cg  D1 , was mounted further back  but generally very much the same as yours,

 

I am glad you didnt cut the frame  to fit engine as this destroys the strenght & integrity of the frame loop,

 

Anyway great job and they do make a nice cruiser, Regards Eddie.

P.S. i can e-mail some photos if your interested,