I was in a similar situation 'cept I buillt my first lower about 18 months ago. I went ahead and bought a RRA upper for it and then later went for a H&R Service Grade Garand. (Just got it a couple weeks ago.) If I was to do it over again, I might get one of those Greek Rack Grade garands ($295, IIRC) and refurb it with a .308 barrel. With the lower cost of the Greek Garand, you might be able to ...
(drum roll, please)--> GET BOTH!
You could buy refurb parts for your Garand as time/money permits and you'd have a nice new Evil Rifle to shoot in the meantime.
After I finished my lower, I could not wait to get the upper... If I had only enough $$$ for one of the above, I'd get the upper...although the Garand is an ultracool weapon to have. Which weapon do you think you'd have the most fun with?
Actually, though, I don't think you can make a bad choice. Either (or both) will be lots of fun.