Working in the SubNesHawk core can be tedious for non-subframe TASes, so while this run is a work in progress, I decided to translate the inputs to NesHawk.
My Submission of Super Mario Bros "Stop 'n' Swop Arbitrary Code Execution" ( https://tasvideos.org/8197S ) unfortunately requires an unofficial release of the Bizhawk emulator. Instead of setting up the RAM and hot swapping to SMB1, you could pretend it's just booting up SMB1 with all the desired RAM conveniently set before the game starts.
This .bk2 file (which no longer uses the subneshawk core) can run on the official release of Bizhawk 2.8, though again, it starts the run with preset RAM. Just pretend there was a bunch of cool subframe SMB3 gameplay right before this starts.