So for BR 8.0 we have the USSR with T-54 (1949 and 1951) vs China with T-59, 69 and 59A. The Chinese tanks are just better. All have stabilizers and a mix of laser-rangefinder and / or APDS/FS shell.
could we see the T-54s so back down to BR 7.7 or see the Chinese tanks go up to BR 8.3 with the T-55A.
No. The Type 59s are only single-plane stabilisers to start, things that work well with the Shermans on short stops because they have good horizontal turret drives; the 59s don’t. The Type 69 is better with dual plane stab + slighter better turret drives but the gun is worse; the APFSDS is very poor, I wouldn’t call it comparable to a T-55A.
Type 59 is fine, though the Soviets should’ve received the T-54A years ago. The other two are definitely undertiered, however.