Tf727 servo questions

Talked to two 727 servo manufacturers about my rebuild. 318 2 barrel /727 weekend driver. Anyway they were saying I need low rev billet servo because I did the tf-tc “shift correction kit” with heavy duty springs. I’m assuming because that servo can’t handle higher pressure.

Anyway I’m assuming the retainer is the problem right? Do I just get a thicker stronger retainer or a full billet piston/ spring/ retainer kit? Is that TSR any good? Price is good.

Also is the DIY accumulator block off rod. What will that give me? Worth doing? Am I asking for too hard of shifts or fun

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