H.P. to weight is key I agree.
But if you are going to do all the hard work of installing an inferior engine and then spend more money to get the some decent power out of it you might consider using another power plant....just my opinion nothing personal.
Here is a link to engine weights...and sure the 2.8 is fairly light...but for a few extra pounds you can get a lot more HP and find parts easier.
http://extremebuggies.com/HTML/enginewts.htm
How much does a Zuk motor weigh?
I've done several conversions in buggies and Jeeps and know some of the headaches. I also know what it is like to put an inferior engine in and regret it...in fact I yanked it out a year later and put a bigger engine in.
Lastly...you are posting in a Sand Car and Dune Buggy Section.
To find performance parts do a Yahoo key word search on
"Ford 2.8 performance"
Happy Trails...
<font color=blue> JimS</font color=blue>
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http://extremebuggies.com</font color=orange>