Personally, I wouldn't have bought the car. I might have considered it if all the parts were available.
I just came upon the post while searching forums about a recent fuel pump change that I have made. But I must say wbain, I'm glad I didn't take your advice. My Mercedes is still going strong with the same SU carb adaptation. I did realize that I had too strong of a fuel pump on. It was an AC Delco from who knows what, and it finally went out. I replaced it with (the name escapes me) a universal one from O'Reilly's it was an inline 7-9 psi. In 3 weeks it burned out leaving me stranded on the road. I was still under warranty so I got another, 3 weeks later, the same thing, stranded on the road. I have now changed to a Mr. Gasket micro-electric pump, with a 2.5 to 3 psi. I think the problem before was too high pressure to the carb, causing some driving problems plus causing back pressure, which in turn burned out the fuel pump. Anyway, I hope I am right. It has only been two days but the car runs better than ever. Starts even easier, runs quieter, still kind of lame on power, but hey, it is a single SU carb.
Overall, if I had to do over again, I would still buy this car again, I have no regrets. Yes, I get frustrated, but every time I drive somewhere, and someone yells out "hey, cool car" it makes it all worth while.