The intake ports on the 85HP are 5/8"; the ports on the 115 are closer to 15/16". Generally, the 115 carbs will waste fuel unless you have the ports enlarged. It would also be better if you used the 115 cylinder heads.
I run a set of 74 135 carbs on my 79 85 hp engine-but I did port the block when it was down for overhaul and I added the intake filler blocks. I run the 135 carbs jetted as is. Stock heads. You should be ok running the 115 carbs. They might overfuel slightly on a stock block, but you should see some top end rpm gains. I'd follow ezeke's recommendation on the heads.
