750K2 / 400F Caliper pistons interchangeable?

[Lobo]

I've a badly pitted 400F caliper piston, and a serviceable '750K2 piston.  They're dimensionally the same (externally).... but the '400 piston has a blanking plate in its end....versus the open ended 750 part. The 'blanking' plate rattles, though is captured in some way that I haven't yet fathomed.  That said, I don't think I can transfer it across due the 400 piston appears to have a thinner wall where this plate fits.
Any comments on whether I can use the K2 piston... and if I have to somehow mimic this blanking plate.
Cheers...

[Bryanj]

Yes you can but you may get the dreaded brake squeal due to no nylon washer between pad and piston

[hairygit]

But, on the plus side, if it squeals you know it's working/ not siezed! 

[Lobo]

Thanks Bryan... Assuming then OK to simply install the open end against the pad.
Cheers

[SteveD CB500K0]

Kevin400F (Kevin Hunter) on the .net site makes these from phenolic resin.

Quite a few members have used them - some from here!

Steve