Engine build up

[JayDubBlazer]

Last year I put a GM crate engine in my truck. It is listed at 260HP and 350 ft-lbs. Here are the other numbers…
• (4) Bolt main block with a (2) piece rear main seal.
• Cast Iron Crank.
• LT/LT4 Powdered Metal connecting rods.
• Cast Pistons, (dished).
• Hydraulic flat tappet cam, (.383” intake / .401” exhaust) and a 112-degree lobe separation.
• Cast Iron Cylinder heads with a 76cc combustion chamber. (Non vortec design)
• 8.5:1 compression ratio.
Currently I am running with a performer intake, 1406 Edelbrock carb, HEI, and headers.

Here is my question. What do I need to do to get is up to about 330-350 HP and 400 ft-lbs.? Also could someone explain why performance heads have smaller combustion chambers? What are the difference between hydraulic, mechanical, and roller lifters? What role does lift play in the heads isn’t just all the duration the valve is open?