92Mustang92

Recently my transmission starting scratching into fourth gear. Its the stock t5 has anyone had any experience in cost to have them rebuilt? I might want to just get something better though because I am putting in heads and a cam. Would the stock transmission hold up or is it better to get something more heavy duty? I figured since I had the transmission out I'd put a clutch in. I was thinking about a McLeod. Anyone have any ideas about a decent clutch that can handle up to 500 hp? Thanks