757jetjockey ----
if the captain's incapacitation occurs concurrently with EFATO before V1 stop after Go----35' vertically and 200'/300/ horizontally is all you may have---IFF {IFF= if and only if} the RTO/OEI--ops- are done to certificated air carrier standards--that you've briefed--
if there was no EFATO just incapacitation then 80 knots is a good number---still in the low speed regime---pilot incapacitation to me is no reason to risk an RTO--in the high speed regime past 80 knots--of course in such a situation--you'd be PIC and it would therefore be incumbent upon you to carry out whatever action in your view are required to ensure safety of flight---For instance you don't want to make a overweight landing [for whatever reason] and and decide to stretch it to 100knots--as long as you do it safely and with a good reason--but 80 knot is a more reasonable number in most events---
Edited to add: Good reasoning
