Ultramax used the same spindles for ages. I bought them from them for my Octane Blaze no problem. Like XXX40 I thought they were 10 degree. I would at least call them and let them know what you want. Theyre probably the most helpful of all the manufacturers I have dealt with.
I’ve ran newer spindles on my 04 octane, spindles for the era weren’t stepped, bent one and could get the hub off indoors so went with the newer spindles. Was also told the c4 L blocks can be retrofitted haven’t tried it though don’t have mine anymore