I am a newbie to you somewhat slanted world but I have some questions...

"Slant six project engine-never assembled. New forged pistons, rebuilt rods, crank ground, assembly balanced. Block bored .060", new cam bearings, Head rebuilt, ported and polished. Have new rings, bearings, oil pump, competition cam, lifters, timing set all in the box. Have original slant six intake modified to accept a GM T-3 turbocharger from a V6 Buick. Have the turbo assembly and Q-jet carburetor, turbo is loose and needs rebuilt. All new parts and cylinder head have been in dry basement storage for the last 15 years and are in new condition. Engine block has been in barn storage and has surface rust and would need a hone to freshen. This is a .060 over 199 cid (rare); the shorter stroke motor works better with the turbo than the longer stroke 225"

Guy is asking $500 worth it? Would it make a decent street motor?

The forged pistons alone are almost worth the money. I'm a little confused on the modifed intake that will accept the turbo, usually it's the exahust manifold that is modified.
The "smaller stroke" I would assume is the 170 bored over?? The 198 is worth a lot due to the rods which has a high rod ratio and is popular to convert over to the 225. I would argue that the higher reving engines will respond better to boost than a lower grunt engine, IF you plan to build it for boost. You can pm me with more boost or building questions but I want to see what other people have to chime in before adding anything else.

The modified intake may mean that an adapter has been used to adapt the three bolt out let from the Buick turbo to the 2 bolt inlet on a single one barrel manifold.