l99 and lt1 blocks are differant. the l99 has the same bore as a 305. the biggest you could go would be like 320 ish cid, bored out .30 with a 400 crank. but youd still have crappy heads with small valve and lots of shrowding around the valves.
just start off with an lt1, it'll make more power.
The L99 is not the same block as an LT1.
The L99 has a 3.75" bore diameter where
the LT1 has a 4" bore diameter.
I would only bore the L99 to .030.
But its easier to build an L99 stroker
by using an LT1 crank to make a 5 Liter or 305 cubic inches.
Ive got one in the Blue Snail
and it makes just about as much torque as a stock LT1
and gets better mileage cruising. I call it an LT9, LOL!
Theoretically the L99 block should be capable of reaching about 360 cubic inches. That is .030" overbore with a long 4.00" stroke. If you were to do the same with an LT1 block, then you would have ~50 more cubic inches.