Headroom and Single Handing
Last fall I acquired a 1980 36' S2 11.0 aft cockpit. She is just shy of your 6'4 headroom request at 6'3 listed in the specs. The center cockpit version seems more rare and a little more pricey, probably has similar headroom. After researching and looking at many boats, and sailing not a year yet, I find it to be a solidly build boat, reasonably fast for size and moderately heavy displacement,and am very happy with her. Its has comfortable accommodations... but its shy of your 6'4
Although it's taking some getting used too, handling a 36' boat alone is working. I agree with the aft led lines, a must for single handing, and an added autopilot I've found a huge help ... you do have to leave the helm to raise or drop the sails or tack, going aforedeck to deal with fenders, or just to go below to grab a soda or a jacket. You can lock the wheel or tie off a tiller, but that's not quite as reliable the longer your away from the helm. For long passages they say a wind-vane steering system is useful but I'm not there yet... I've found the mainsail is big and a fight to control when dropping, especially when taking it down in a breeze, and will add lazy jacks soon to help with that...but even without lazy jacks, the mainsail is barely manageable in a good 15-20knot breeze by myself (thanks to my buddy the Autopilot) Everyone Ive gotten to know says lazy jacks or a Dutchman system will make it easier, and safer, when alone on the boat. A mainsail furling system is a more expensive upgrade I am not considering now, but a roller furling jib is invaluable when sailing by yourself....somewhere I read that a cutter, ketch or yawl rig allows for more easily handled sails as they can be smaller relative to equal sail area on a larger sloop rig,...I can see their point. Downside is more complicated to sail, (everything is a trade-off) but if you're looking at boats bigger than 33-38ft, that might be an option.
I would say docking the boat on my own when the wind is up is my biggest challenge, but it is still manageable. More weight is more momentum, harder to fend off from the dockbox (my biggest enemy) especially when the wind starts to shove her over.... I can't imagine handling a much bigger boat than this alone. Lucky their are some really awesome people on my dock that are happy to help when they're around. Last thought... if you find a boat with your basic necessities, its general more cost effective than adding it on later, its starts to add up quickly, I'm learning that pre-warned lesson first hand.