Welding on head Bolts. Advice Needed

[19Fordy]

I would like to reinstall my 8BA oil filter on my engine that now has 59AB style heads that i still want to use. These heads do not have the 3 bolt holes originally provided for the oil filter.

I can make an adapter plate (shown in cardboard template) that will fasten to the 3 current head bolts IF I weld smaller bolts needed for the oil canister to the top of the head bolts. the head bolts are Grade 8 7/16-14. The bolts being welded to the head bolts are grade 5, 3/8-16.

1st photo shows current grade 8 head bolts installed. 2nd photo shows desired outcome after welding and finishing. 3rd photo shows close up. 4th photo shows card board template for adapter The lower portion will be attached to the 3 head bolts. The canister will be bolted to the top portion of the template. Last photo shows the early style 50 merc oil canister in relative position.

QUESTION: If I MIG weld the smaller bolts to the grade 8 head bolts will it degrade the hardness of the head bolts whereby they will no longer withstand the 50 FT LB
torques required when securing the head bolts? I don't want them to snap.

I can't find any head bolts threaded at both ends. Wonder if they are available. What are they called? Last sketch would be ideal, if available. Thank you.