R129 SL500, which engine?

I have a question to the experienced R129 municipality. I can possibly get a very well-kept SL500 from 1992, i.e. an early model. The power hubs are different, both early models are often given 326hp, from about 1992 on 320hp and from later models 306hp. According to Wiki the first engines are identical, type M 119 E50. From 1992 on with less hp and torque, why always. In the later models from 1998 on the M 113 E50 was used, few r power and less torque. As far as the facts are concerned, I myself drive an S211 EZ08 with the M273 KE55. Best Engine ever, in my opinion. Now the experts are asked: should one buy an early R129 with the M 119, if it is maintained or rather watch to get a late with the M 113, because the engines are more modern and the complete technology more sophisticated? The vehicle would be a pure fun vehicle for the summer, annual driving performance perhaps 5000 to max 8000 kilometers, with the claim to become a youngtimer in a few years. So fuel consumption is to be neglected. I say thank you for your information.