My suggestions is try and find someone that wants to sell a bike and trade your bike on in something that fits better. YOu might even be able to do a straight up trade for a similar vintage road bike. The bike you have now looks pretty solid. You could sell it if you have enough cash to buy a larger sized bike of some kind before getting rid of this one. It looks liek you did a really nice gjob on this bike. I think you can find something used that will work out better than this bike. I would look to get something that fits and I wouldn't even mess with buying a longer seatpost unless its like $15.