Since the OP is planning on getting new wheels/rims anyway, I see no compelling reason not to switch over to the more popular 700c size. Doing so makes for much better tire availability and the chances for good tire sale prices are greatly improved. In addition there's a bit more frame clearance so you have the option of both narrower tires that are available in 700c and running wider tires than would fit the frame if you stay with 27". That also gives you the option of fitting fenders with a greater range of tire widths. So there are some significant advantages to switching and I can't see a real downside unless possibly if the current frame has a really low bottom bracket and is subject to pedal strike issues when cornering - seems unlikely for the OP's frame.