SkiffRopes sell Allen 30mm Dynamic and Plain Bearing Blocks.
See manufacturer product range info at: https://www.allenbrothers.co.uk/range/?pid=cjlf6loze0003d1v4cxxauoqq&cid=cjlf6kjpg0001c3v4ks3pm3xq
SkiffRopes usually keep the following in stock:
Allen A2030 Single Block
$24
See manufacturer product info at: https://www.allenbrothers.co.uk/product/a2030-single/
Allen A2030HL High Load Stainless Steel Sheave Single Block
$55
See manufacturer product info at: https://www.allenbrothers.co.uk/product/a2030hl-single-high-load-stainless-steel-sheave/
Allen A2030XHL Extra High Load Stainless Steel Sheave Single Block
$194.45
See manufacturer product info at: https://www.allenbrothers.co.uk/product/a2030xhl-black-extreme-high-load-black/
Allen A2031XHL-873 Extra High Load Stainless Steel Sheave Single Block With A.873
$230
See manufacturer product info at: https://www.allenbrothers.co.uk/product/30mm-extreme-high-load-block-with-a-873/
See product drawing at: https://www.deckhardware.com.au/assets/brochures/A2031XHL-873.pdf