Need your advice for new engine

[vincent]

Hello folks
I bought a 34 Sedan recently with still the original engine/gearbox/differential. With somer help from you I got the thing to run as good as it can and reached a genuine 100km/h on a test run but there is not much more speed available due to not enough power output. This little engine will need a lot of work to be ever able to cruise at 65 mph and 2500 revs.(I doubt it can do it)The gearbox became very noisy in first and second gear recently, the clutch will need renewal as well and the motor has a ticking noise when hot and uses a lot of oil. I realized that it will take a lot of money to rebuild all this stuff and I will still end up with a lowish power output from that "small" 3,6 ltr engine. I need more cubics and more power as I plan to pull a small trailer with my motorcycle now and then.
So now I am looking for an engine with at least 4,2 ltrs, a gearbox with full synchronizing and better spaced gearing (would love a 4-speeder if there is anything available). I can even change the rear axle to something else with an open kardan if a better gearbox would need this done. But if possible I would like to keep the stock axle to stay within the "historic" rules here in Germany.
Of course I can rebuild the differential with higher gearing to lower the revs but I need more torque to pull a trailer / cruise at 2500 at 65 mph.
If anyone has a suitable engine for me and a set of gears or a complete box, I am very interested.
Due to me being in Germany it will need some arrangements to get stuff over here but I can make it happen. So what would be a good combination for my use? 59ab or 8ba or what else? I would really like to buy a good and trusty engine with a lot of torque, accompanied by a sweet shifting gearbox as all the work and parts needed for my heap will add up quickly and use up a lot of my sparetime as well.
Thank you for all suggestions!
cheers, Harty