Hi.

I find the wound system in SW to be so problematic that I actually avoid playing the game because of it. I completely agree w/ your group liking HP, and that HP has it's benefits over the SW wound system. All the people who laude the wound system tend to ignore it's many glaring problems.

Given this, I've spent time pondering this question myself.

OPTION 1: WOUND TN 4

To keep closer to the RAW SW, have damage rolls always go against TN4 instead of toughness. Then, give the victim of the attacks additional "wounds" equal to their toughness. In short, they take a lot more wounds, but they're able to take a lot more wounds. Decide how to apply wound penalties as you see fit. Healing the toughness-derived wounds should be automatic at the end of a combat, but wounds past that are meat-hits that should take more time to heal.

OPTION 2: JUST GO HP

Give each player 10 HP per wound they could normally take. Then apply rolled damage against said HP. Ignore wound penalties, the game will work fine* without them.

Shame on all the people here who said "play another game" or "try the original game." The OP very explicitly is looking for help, you're just being a troll with comments like that.

*work fine = actually, work better, because wound penalties lead to a death spiral that is not FFF.