Cobra Engine Swap...Ways to improve my 98 GT...

[91LX2Bfast]

The 4R70W should bolt up. The Lincoln Mark VIII had a 4.6 DOHC w/ the 4R70W. You may need a few MK8 parts to make the swap work.
My Tbird will be getting a 99+ PI engine in the upcoming months mainly because of the labor involved. It'll be an easier swap then the heads, plus I'll keep a lower CR for doing a power adder down the line.
You can do a 6-8 psi blower setup relatively safely as long as you give it enough fuel and get a conservative tune. There are a number of blower setups that don't have that typical "swoosh" sound at idle like some of the centifugal s/c's have. Any roots blower like Saleen, AED, SVO are pretty quiet including some new centrifugal blowers like the Vortech SQ (super quiet) series. There no reason you shouldn't run at least low 13's with a decent blower.