straight 6 vs v8 starter

[cjoenny89]

When I was putting my truck together and working on the engine where my dad left off after 30 years I found the old v8 327 starter to be junk and I was happy since it was a fresh rebuild 25 years ago lol and when I went to get things going the engine wouldn't roll over. long story short I had a straight 6 starter and I hooked it up and the truck rolled over and started but when it gets hot it doesn't have enough get up. are the starters the same or is the 6 cylinder have less torque then the v8 starter? I have played with timing and when I do that I can get it to start hot but then it doesn't have good power.
do I need a good after market starter or do I just need the correct v8 starter?
Thanks for the help!
Chad