the volvo swap is easy, the head runs, about 200, another 150 or so for the welding and that about it, you will have to make a log type manifold, and run megasquirt type stsyem,
my buddy did this on his merkur and he dyno'd 440 at the rear wheels, but he does have a holyset hy35 turbo on there off of a turbo cummings deisel truck
Are you talking about Colin's XR?
As mentioned above, the PARTS aren't too bad to get ahold of, it's all the fab work required to make them fit. And judging by the original posters posts....he does not have this capability and would have to have the work done....which causes the price to increase by quite a bit.
As I said, there are too many variables in this kind of conversion to give a wide brush-stroke over what the gains/differences would be. No two conversions have even been the same....so how can you say one way or the other? It's all just speculation.
Yes you MAY see power increases if you kept everything else the same if you went from a SOHC to a DOHC. How much? Who knows. All other factors depend on the parts used and the final tune. You could wind up with an engine that gets more hp/tq/mpg if you can tune it properly. You could also wind up with one that's worse.
Honestly the Volvo swap sounds like it's out of your realm of abilities, if not to actually do, but even just to maintain. There are PLENTY of mods for the 2.3T that don't require you to do alot of custom fab work. How are you having trouble VIEWING turboford.org? You can read the entire forum w/o being a member. Also
www.turbotbird.com is a good resourse too.