C-6 accumulator 1970 vs. 1979

I recently got off my rear and rebuilt my 79 C-6. I had a TCI kit. All went fine until the accumulator seals. The 79 has the seal built on to the piston. Looks like it was dipped in rubber (I know it wasn't, it just looks that way)to make the seal. I have a spare C-6 from a 70 Merc and pulled the accumulator out of it to use. The piston uses an O-ring but, the housing and piston are a larger diameter. I went ahead and installed it but got to questioning my judgement. Does any one know if this is going to work? Thanks.