As I've said numerous times...test is the king of all AAS. The only reason to not use test only is to reduce the sides that test can cause. So test only cycles are great. You won't be dissapointed with a G of test.
I've done, and am currently on test only, 500 mgs sust wk. Gains are decent, all depends on how good I'm eating. If you're going to run 1 g of test a wk, I don't think you will be disappointed.
5mg of proscar could be bad for sex drive. im sure the 1g of test would compensate for that while you are on, but when you come off might be another story.
you will have more likelihood of bloating up on 1 gram of test than 500mg deca and 500mg test. Though not everybody will bloat. Most older BB's I know will do low dose of test and higher deca or Eq doses to avoid bloat and other sides. but, in the end, the gains are basically the same.