I find the SC option much more viable for the average Joe than an engine swap. It's way easier (and quicker!!) to accomplish - especially for those of us with limited time, tools and skill (especially skill). Having the carb pretty much sorted out by Moss is a big deal, IMHO.
Personally, I still lust after one of those DCOE throttle-body EFI setups. If the ricers can use them on a Toyota, they oughta work great on an MGB. Imagine tuning up your fuel delivery system with your laptop!!