727 Disassembly and Advice

I've seen some people do some odd things to transmissions over the last three decades or so. I cannot say I've ever seen what looks to be a GM speedometer drive gear put on the accumulator like that. At any rate, you can just discard that and leave the accumulator with no springs or find a spring that goes on top of the accumulator towards the valve body. The spring will slightly cushion the shift, no spring will firm up the shift.

As for the rust I wouldn't be worried about any of that at all. It will blast off in a blast cabinet with glass bead media. Or, as was mentioned you can spin them in a lathe with a scrotchbrite pad.

As for the early '70-back 2nd gear servo, well someone just installed it in favor of the late 5/8" rod single spring servo--for whatever reason, perhaps the original one was worn or damaged. Some folks think the early small rod, two spring servo works better. If you keep the early servo, find an outer spring for it. The old school thinking of removing springs from apply servos is wrong. The whole idea is to get the band off quicker to avoid 2-3 bind or overlap.

I'd not mess with the push button transmission as not much will interchange. That could be a valuable core to someone, and is even more valuable left assembled.