does your grand have a v8 in it already? or is it the I6?
its a great idea to build up a ZJ (if u have the patience, skills and $$$$$) but there is NO need to swap out your 5.2 for a chev 350. there is almost no gain except for a headache trying to get everything in there and getting it to FIT. specially when an intake, chip and exhuast (1000$) will give you TO much power as it is.
u want to start lookng at a place to upgrade, start saving your coinage for axles. to be blunt, your stock ones suck. your rear axle can trussed for some strength, but i kid you not when i say there is NO aftermarket parts for it.
plus, i'll give ya the benefit of the doubt cause ur new to wheelin' you will learn FAST that open diffs (as you have) stink, and lockers and gears will quickly replace teh want for big lifts and tires.
or go big or go home with a full long arm kit
http://www.ironrockoffroad.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=IROR&Product_Code=IR-Z7PLA&Category_Code=PFZto all you AWD haters, i laugh out loud!
i beat the bloody hell out of my 249. they say it doesn't even lock 50/50 in low range, well i'll tell ya i put mine through more crap than most of you rubi owners
and trust me, it worked just fine. now when/if i build another ZJ, i would swap it out in an instant, yes, but if you daily drive your grand in this province, yes id keep it. i have one in my 00' grand and no i woouldn't swap it over. i like it.
my .02