I do have to say there are more than a few very nice Speedsters that are bought new and sold some years later with less than 1000 miles on them , many with less than 500 miles. Without fail they are all aircooled VW powered. They are offered with low miles because the owners found the driving experience lacking their expectation and sold them. I would recommend driving a Speedster with both drivetrains before dropping $40k . The time to do so will be well worth it. I have been an aircooled guy for over 35 years and was happy to switch to the modern fuel injected technology and drivable power that encourages me to drive my Speedster many thousands of miles with a giant smile on my face as I zip around town and on the interstate with 180hp and 160ft/lbs of Suby torque on tap. The closest thing you will get to that with an aircooled VW based engine will cost as much or more and will be in most cases fragile, finicky and in the end break your heart and drain your wallet. Been there and done that.
That said. I hope you enjoy your choice without regret, as there are many on this site that love the vintage aircooled approach. I hope you become one of them in the end.