Don't pay any attention to that warning status thingie, believe that has to do with the amount of emails you get in......
Yea, the 305 is pretty anemic, so-to-speak. It has small valves, small bore, heads have a tendency to crack, bigtime! Other than that, its a SBChevy, which, in itself, isn't bad.
Try the lifters, they're not much at all, then try the gears, if you need some converter, go pick up a new Vega unit at O'reillys or Autozone for about 100 bucks. Like I said, it'll last a while behind the smallish 305.
I've never looked up the #'s on the 305, but when new, I don't think they put out more than about 185 to 225 horses with a big tailwind! hahaha.....this can be helped with a little 500 to 525 cfm carb with vacuum secondaries and a aluminum intake. Of course, you got the headers going for ya, with that cam, and the timing anywhere near right.....you out to have a good, dependable 245 to 270 horses on tap.
With the 3.73's, you'll be liking it a whole lot better! Be like a whole new car! 3.55's with that tall a tire.....it'll be peppier quite a bit, but you aren't be causing any big black marks at any redlights.....you'll need 3.73's!
And/ Or a good set of heads.
Next motor you decide out build or get.....get yourself a 350.....same money, alot more performance potental for the same amount of money expended. Its easy to build a 500 horse smallblack for under 3 bills......