Old Briggs head gasket swap - cast or aluminum?

I pulled the head and I was pleased with what I saw. No ridge in the cylinder and good valve action. Lots of carbon but the valves and seats look good.

I am going to put a new head gasket in but I need to know if my engine is cast iron or aluminum because that dictates the correct head bolt lubrication and torque. I held a magnet to the block and head and there was no reaction. I assume everything is aluminum but would appreciate it if someone could confirm that for me.

My engine data is as follows:

MODEL: 061102
TYPE: 0133 01
SERIAL NUMBER: 6312303


Thanks for your help.