When it comes to electric, I always run to the professionals. I can see how the cost to install a new type of outlet could be off-putting, but I’d at least consult with a local professional electrician and get the scoop.
I think there are no bad choices here:
1) Not sure, but could an electrical pro swap out your 3-pin for a 5-pin? I ask because it seems inexpensive, and I have a memory of seeing 5-pin to 3-pin adapters, so then the same outlet could service both machines. Talk to a pro, a quick phone call should get you quick answers and from there it’s an easy decision.
2) Big picture, if your worst-case scenario is that you end up with an FB-510, then you are in a very good position 🙂
Over 18″ of rip capacity, 4 HP? I know a number of professional woodworkers who have built successful careers without owning a bandsaw of such capacities.
Good luck, post pictures once it’s installed!