100' of chain will essentially fit in a milk crate, and the PSC34 has an unusually large forepeak due to the long bow overhang.
I think you could put 300' of chain on each side up there without difficulty. But, it would weigh 800-900 lbs., which I think is too much for the forepeak.
On the starboard side of my PSC34 I have 100' of chain backed with 100' of rope. It would be no problem if I had another 100' of chain up there. The rope is FAR bulkier than the chain and there's room for more.
The port side has just as much room. It has an all rope
rode that came with the boat. I am not sure how long it is, but it is fairly long.