Speaking as a (Lacto-Ovo) Vegetarian, I'll throw in my 2 cents. If your goal is to pack on muscle and strength, you need a lot of protein. A lot (2gms per pound of body weight is the rule of thumb). It is highly unlikely that you will find a vegan source that can be absorbed as readily as, say, eggs, in terms of protein, or something that packs as much punch, without paying for it in cost when you're eating in that quantity.
I only started eating eggs four years ago, and I've been lifting for roughly nine. I found that adding eggs to the diet was a godsend for me. I was able to go from a 135 pound bench then to about 245 now (4 rep max).
I have actually been thinking about going the meat route, except for Beef. Culturally, I'm not sure I could handle eating that meat. Something to think about I suppose...
You can avoid beef but still eat chicken, pork, and especially fish and get a TON of protein, man. Beef is awesome, but it's not like other sources of meat aren't as good, all the stuff I listed can still be excellent sources of protein.
Are there any hydrolyzed plant proteins available? I would imagine that this might help with the absorption issues somewhat. Also out of curiosity, are there any vegetarian super-isolate proteins out there that manage to remove the other bio-actives, e.g. isoflavones?