Resleeve a stock cylinder

Not sure what ya mean in the last post but yeah thats what Vitos does.
They bore out the stock sleeve then press in the 72mm sleeve.
Your original porting should be unaffected although you prolly want it ported more to take advantage of gain in CC's the new sleeve offers.
 
Vito's cylinder "kits" are completely new castings head and all.

Vito's also sells a resleeve kit which does exactly what the OP is talking about. You can find them brand new on ebay every so often for $250 or so. If you have access to a machine shop or know someone it's a relatively inexpensive way to Big Bore your cylinder but getting a sleeve pressed is usually about $150 affair. $250 for the kit plus $150 to press the sleeve and another $150 to port it... Might as well have just bought the vito's BBK replacement kit...
 
Ok,that's my project put a 72mm sleeve into a DT 200 cylinder without the YPVS and run with the blaster CDI,flywheel and stator. In 2006 a put a complete Dt200 engine with a fonctional YPVS and all the wiring harness. 2 atc250r radiators, PWK 35mm carb,V-force 3 machined head +6 vitos cranks with stuffer bloc. Great upgrade but there to must parts of the DT NLA 1986 it's old a little bite!