How to add an extra lobe to a cam?

I am working on rebuilding a BMW N54 engine, and would like to add a triangular-ish love to the cast steel exhaust camshafts so I can drive a high pressure fuel pump off it. The idea would be to replicate the same love profile found in one fo the newer BMW engines like the B58 so I don't have to design a solution from the ground up.

These are the ways I'm thinking I could get this done: 1) built-up material by TIG welding the cam and then have it grinded to spec (time consuming, may weaken the crankshaft) 2) fabricate the lobe in sections (2 or 3), weld them together to the camshaft, and then have it grinded to spec (less time-consuming than #1, but may still weaken the crankshaft) 3) Reverse-engineer the original crankshaft, create a 3D design with the added love, have it fabricated (time-consuming, fairly expensive)

Any thoughts?

EDIT: I am so thankful for all of your responses! I think I have figured out a 4th path to figuring this problem out:

I initially thought about creating a new housing for a cam-driven fuel pump that would be mounted on the same place the old HPFP would, but I recently found that's unnecessary. Late N55 and S55 engines already have a timing-chain driven housing for either one lobe-driven pump (late N55) or two (S55). The housing can be had for a couple hundred bucks, and greatly simplifies the hardware requirements for my project.