i did a conversion a few years back
gen2 liberty with the works v7 sti motor, 6 speed brembos, sti interior, all the legacy panels etc etc was a great car was quick and looked awesome
spent a shitload of money tho
im one of those people that get over cars pretty quickly so i only had it for about 2years and then had a test drive in a bug sti, the car was stock and was so so much better to drive, ended up picking one up with 80k on it stock for less than what i payed for the conversion
my opinion is if you love your car and want to convert that then do so but be prepared to spend twice as much as a standard turbo liberty
a few other things is you will have to get it engineered to do it properly too
also if you bought a b4 not only would it be cheaper in the long run you get all the factory options and everything works, you can still add all the legacy gear too it and single turbo it etc, changing an engine is so much easier than a full conversion
i have done 2 conversions and helped out with a few, at the end of the day the only reason i did it was because gen2 libertys arent turbod in aus and i always wanted one, gen3's came turbo's standard

id just put a 6speed and ej257 in a b4 add a few legacy bits and be done with it if i were you