Okay, I will chime in with the same advice I usually give. I would work to increase you strength and blocking first. Yes you back up now and think that speed and agility will be important and could help out your build. If, you ever want to be a starter, increase the strength and blocking first. Take them to like 4th cap at least, 74 without equipment and you can train your other skills while you get there.
At RG in order of importance of stats and where I suggest you try to get them:
strength 74 (min)
blocking 74 (min)
agility 68
speed/confidence/vision 60
All equipment in strength, you can buff you blocking points with VAs and the like. Also, the faster you get str/blk to a high cap the more you get out of the automatic level gains. They aren't as good as a C, but still worth getting to a high skill total early.
I have built a few olinemen and I know I only have about 5 seasons experience on GLB, but i do a lot of research.
*last note, I know SAs sound cool, but don't waste points on them until later in your build. Think of it this way, if I pump the crap out of my run block tree, but dont have the str, blk or agility to actually see any bonus from these SAs, they are a waste.
The numbers that I posted above for my suggested build will take a while to get there now that you are already somewhat into your build. They are also exclusive for a RG, LG builds are completely different I believe.
EDIT***The reason to get up to 60 in speed is if you are being used on pitches, screens and for pulling.