Now if on the strip.... I am not too familar with the stealth R/T. If its a turbo I think you will lose. 300HP...IIRC. the N/A one make 225hp so it would be a close race and IMO go to the SHO on the long runs.
If It's a Turbo it will say on the doors "R/T Turbo"
If it is a turbo, it's 320 horses, the 94+ were 6 speed getrags......run mid-high 13's, and off the line they will destroy you (I know!)
If it's a non turbo, they won't beat you off the line (no 315 ft-lb @ 1500 rpm!), and you'll pull. Those motors have pathetic top end power (I know!). At 7000 rpm the turbo cars have almost no power and the non turbo's aren't any better.
I've raced several SOHC ES Stealth's and 3000GT base models at tracks, they are easy to beat. I've only gone against one DOHC 3000GT SL (same as R/T Stealth) and I was starting to pull at the end of the 1/8th pretty well, had about 4 lengths but it was a slushbox. (FYI I ran a 10.5 @ 74 in a 99 SHO) I would guess they're about equal to a Duratec Taurus. I've heard low 15's listed by them but I have yet to see an DOHC N/A 3Si run anywhere close to that.
If you're MTX is stock, the race should be close but i'd put my money on the SHO, especially in the quarter mile. The two cars have relatively the same amount of power but the SHO is better high end and the 6G72 is better mid range. The SHO I believe is quite a bit lighter, i know my friends Stealth R/T turbo and VR-4 are both over 3800 pounds, granted they have AWS, AWD, and a bunch of electrical crap, but even with that removed I don't think it's going to be as light as a Taurus - but I could be wrong.
In any case, they aren't very light cars, so if he's thinking it weighs as much as an eclipse and thinks that's why he can take you, he's in for a rude awakening.