Re: 156 1.8 engine rebuild in situ?
yes you can definately drop the sump to replace the bottom end on the 1.8TS.
its very encouraging to see you've already thought about piston ring losses and plan to use a glaze buster. they really do work, and you wont need to use new liners, but you will need to use new rings on every piston. the great thing about this method is you will regain perfect compression and reduce the oil consumption that plauges the TS engines.
personally i would get a cheap scrapyard engine (£150) that had good even compression, then do the cambelt job while it is off the car, then fit the engine. total cost will be less, plus its quicker and easier. but for personal satisfaction, and if i planned to keep the car long term, i would use your method.