All current Novarossi sleeves are 19.5mm in diameter and all are 16.2x16.8 bore/stroke. The only uge difference is the 3mm or 2mm thick upper edge and even then with the right button head and the right amount of shims you can make it all fit.
Other difference in onroad P/S sets is the height of the exhaust port, that can differ from 7 up to even more than 8mm but mostly they are 7 to 7.5mm. Even if you buy the same P/S set the exhaust can be different, nothing to worry there, it will determ the balance between top RPM and bottom power.
Last year I bought a cheap offroad JP P8 P/S set (2mm edge) and placed it into a JP Eagle which normally has a sleeve with a 3mm edge, the original Eagle button head needed a 1mm extra shim but I used an old button head.
The funny thing is that all Novarossi engines I have seen the intake ports are always on 65 degrees timing. As it was an offroad the exhaust needed to be raised with at least 1mm and the engine is still going strong.
I have builded many engines combining sleeves with diferent crankcases and realy, there is no special story with the sleeves.
Over here the Kangaroo is about 350 euro and the 35+ about 420 euro, for the 70 euro I would go for the 35+
With the upcomming season our club will be running the N21-5T engine. Ofcourse I turned this engine inside out but we are amazed how this engine is configured for just 129 euro. It is almost timed as a Kangaroo and for the modders it is easy to get more out of it. Also here yhe P/S set does cost 100 euro and yje whole engine (special club price) is 129 euro..... The choice is simple