Hi John,
yes, the 'osmocom' way to integrate your L1 hardware would be ot use osmo-bts as basis. It already supports one existing L1 (for the upcoming sysmocom BTS), and Andreas has been working on supporting some hacked-up OsmocomBB phones as alternative L1 for it.
osmo-bts then connects via Abis/IP to openbsc (osmo-bsc or osmo-nitb).
In any case we would love to hear more about your L1 hardware. Can you tell us more about it?
Regards, Harald