Seat Posts for '86 Fisher SV-18 TC

[jbjork70stpl]

I just purchased a used 1986 Fisher SV-18 TC. The boat came with only two seats/seat posts. I need to buy at least 2 more seat posts for the rear seats and one more post for the casting deck. My problem is that my Fisher has built in seat post "holes" that are built into the floor/deck frame. The post hole is basically a 2' inside diameter pipe. I need a seat post to fit down into the post holes, however I don't see any 2" style seat posts. Everything is bigger or smaller diameter.

What do you other Fisher owners use? Is it possible to convert to newer style seat system? Can you buy the original Fisher style seat posts? Any help is appreciated. I will try to post some pics for reference.