Re: 302 and 351 advice please.
I currently have 2 XE's, both 351, one with a single rail box and borg worner diff 2.75 ratio, engine is dual fuel, not a lot of HP fairly std, will only rev to around 4500, runs mainly on gas and really well. I get around 22 liters per 100km/gas.
The other is a little hotter, has a cam with just over .5 lift and revs well to around 5500, toploader and a 9inch diff with 2.75 ratio, (had a 3.5, too much rpm at top speed) I get around 18-20 liters per 100km, on gas. Not sure on the HP but should be over 300, This engine has open chamber heads with around 150psi compression.
Definatley go the 351 and make sure its dual fuel, you'll have heaps of HP and heaps more torque than the 6cyl had.
If you can't afford hardened seats or you don't know if they are, buy a Flash lube kit that runs to the carby it sucks in fluid at the rate of 1mm per litre of gas or fuel, from a 1litre bottle. visit the site and check it out, flashlube.com.au
Hope this helps....Paul