You want my opinions on the top swap?
Some will say go for it. Others will tell you not to waste your time. For me, I used a low mileage L27 as the core replacement for my shot L67. So far, the build has held up well, and with the sole exception of chasing knock gremlins (my cat was the biggest contributor), it has been reliable. I will know much more when the trans install is complete and I can drive the car alot more than 1k a year.
If you plan to run only at or slightly above stock L67 levels, an induced L27, esp. one that has been well cared for, will hold up well I think. If you DO plan on going past stock L67 levels, I suggest going a few notches richer than normal. This will keep you from melting the pistons since they are not coated like the L67 pistons. Otherwise, stick with the L67 setup from the get-go.
Keep in mind I am not mentioning the HD trans. No matter if you have the L67 or TS'd L27, it'* a given you should have an HD trans
Welcome, downwardly mobile yuppies, to the dawn of the Age of Nefarious.
1993 SSEi - FrankenJinx - dead and gone.
1994 SSE (136K strong) - 180* t-stat,HD alternator, most unequipped SSE on the club, XM radio, Kenwood CD/MP3.
2006 Chevy Malibu Maxx LTZ - Custom 2.25" manifold-back exhaust w/FM-80. Probably the only Maxx with this system.