Jeep 4.2 to 4.0 cylinder head swap out has anyone here done it

[Guest]

I've got an 88 Jeep Wrangler with a 4.2 liter with a Mopar fuel injection .. I'm wanting to Swamp the 4.2 head for a 4.0 main reason my 4.2 head has been milled and is requiring me to run higher than 91 octane fuel this is getting expensive on a daily driver so instead of trying to make a thicker head gasket or playing around with what may or may not work on this hed I figured I just swap it with the 4.0
now from what I've been told I need a 4.0 head with a 4.0 exhaust manifold and valve cover I'm also seen that there are some places in the water jacket I will have cap off ..
has anyone here done this swap and how do you do it how well does it work I I need info badly before I go spending money I really don't have..

Thanks

[mujeeper]

I have not, but I'll throw my 2 cents into the pot. Whatever the cost is to do the work, what is the break even period for cost to do work vs amount of money saved spending (~$0.20 per gallon) considering miles driven & any change in mpg from the mod?

[Guest]

it takes me from premium back down to cheep gas which would save me about $2000 a year.. technically I need to be running about 97 to 98 octane at this compression I've got a terrible high end detonation problem