[JP Noonan]

I'd say anything over 2.2 maybe 2.4L you also have to look into non-stock cooling. I.E. a big honkin' oil cooler, with a inline thermostat. Also either a upright 911 type shroud or an electric vertical fan setup (good luck finding one of these with an alternator backet).

I agree with DD, the MS 2.7L and Fat's 2.8L are not long lived motors. I dunno ask Mark how long they usally last.