There might be custom billet steel heads that people make specifically for pullers, but I do believe all heads are aluminum. Heck almost all air-cooled engine heads are aluminum. At least in the small engine world.
I do have this late 1930s Briggs and Stratton model "A" engine with a cast iron head, but that's the only small engine I've seen with a cast-iron head.
That's really strange with the link not working
Edit: may have figured out why the link won't work and why the website title is censored. Stumbled across this thread by chance:
https://www.onlycubcadets.net/forum/...ad.php?t=47315
Posts 6,7,8 and 11 to be exact.
__________________
'70 107 with k301 engine swap
'71 106 with 38" deck
'70 147
R with factory replacement k321, 42" deck
'61 Original with 38" timed deck
'63 70 "pinkie"
1863 with 54" deck
'46 Farmall H, '50 Farmall Cub
105 x2 (parts)