Submitting a Form 1 is a piece of cake. If you want a SBS, then build yourself an SBS for the sake of $200 and an evenings time.
I suggest you go to www.silencertalk.com. Its a good group over there. Friendlier than AR15. There is a TON of stuff on doing the forms. I'd also be happy to help.
If this is a one-off, then submit as an individual. This requires fingerprinting and the signoff of your town's chief law enforcement officer. If you think you may have a developing addiciton to SBRs, SBSs, suppressors, machine guns, etc. Then you should set up a trust.
Once you set up