I can’t find a kelvin style shenzhou art anywhere. It would be a matter of repainting and relabeling and swapping out nacelles. Problem is it hard to tell on the kelvin which tube is the nacelle. Also I’d like to see D’kyr type Vulcan ships form Enterpise refit as a Starfleet ship. Since that class is larger and faster than the Enterprise i would imagine they would be top of the line close or top of the line ships during Discovery and TOS. I cannot find any fan art of that either but I like to picture them with hull labeling and federation nacelles instead of rings and a federation style coating. Same with the Andorian ships in enterprise. In fact many starfleet ships seem to derive from a blend of human and Andorian styles. Ships with seperate primary hulls(saucer) which are similar to Earth ships and secondary hulls(engineering section) which are similar to Andorian ships may be the result of combining design philosophies for maximizing ships capabilities. And the curves of the Galaxy class and especially ships like the intrepid, sovereign, and inquiry classes show their Vulcan influence. They are all blends of designs from Earth, Andoria, Vulcan and Tellar, and likely other federation members as well. If the Klingons joined the federation it would have a major impact on ship design. It would lead to their ships being refitted with each other’s tech and new ships being designed which combine design philosophies. A future flagship might look like the STO Enterprise F but longer and with the Klingon dolphin tail shape near the end. If it weren’t for the Andorians and Vulcans and perhaps tellarites the Enterprise D would not be the Enterprise as we know it.