I think you are mistaking the extensions for when you take a PV out. 80/88 is a good start, it won't be lean, if anything, it will be slightly rich depending on the size of the original power valve restriction.
I am not sure what exactly you are asking now though but to go through my entire deal
1 - 80/88 with a PV in the front, a PV plug in the back
2 - Make sure the PV plug doesn't hit the main body when you assemble, some need a little ridge ground off because they hit the main body
3 - I think removing the rear PV is good, certainly not a must, but it gives a consistent fuel flow when the engine is working the hardest.
4 - The jet extensions are good if you need them, but you generally need a new float to make sure the float can travel fully
5 - The jet extensions should not make it run leaner, in fact, it should get the jet deeper in the fuel
6 - Finally, remember, float level is a tuning tool, you can go up and down a little to change head pressure at every circuit. It doesn't do a lot, but it is an adjustment in itself.
7 - Make sure you have good fuel flow to the carb, pressure doesn't need to be high, but good filters, properly size lines, etc are critical if you are running hard
Hope this helps