Use the Vortec heads. They flow as well if not better than the LT1 head and don't require welding, etc. that the LT head does to make it work on a non-reverse cooled block.
The Vortec will not allow for more than about 0.460" of lift w/o clearance between the seal and retainer being too close and the springs themselves are too weak for most aftermarket cams so they have to be changed.
There are spring packages that can be used to get around having to machine the guide boss for clearance or you can have the boss shortened and cut for seals if you prefer.
There are a lot of threads here and elsewhere on this, CLICK
for some more info on Vortec heads and mods to them, etc.