If you have papaw/papaya seedlings with 1-2 cms stem diameter, use the V top grafting. However, with large tops up to 20 cms in diameter, you use a W graft,cut 99% of the leaves, you must fasten at 2-3 places with a plastic zipper strip, spray with various fungi-bactericides, double cover with opaque plastic bags to maintain humidity. Try and match the diameter of the crown to the rootstock. For the huge crowns you need a strong sharp long knife or a very thin blade hand saw. You should draw the cutting lines with similar complementary angles so that the 2 parts will fit into each other. The photo is from Ariel’s tree in Israel.
Paul Williams from California tried this W graft of a Sunrise Solo bisexual papaw weighing five kg of apex on a male rootstock. The apex was taken from an 8 years old, 5 metres tall papaw and was grafted on a 13 cm in diameter male rootstock. The graft was conducted on July 2005 and since then the apex grew by one metre.