1903 Springfield Mark I - Cutoff Spindle Spring & Plunger Substitution

I have been on the hunt the past few years to obtain the parts needed to return one of my 1903 Springfield Mark I rifles to proper Pedersen Device configuration. I have obtained all the parts minus the spindle plunger and spring. I am wondering if I may be able to use a shotgun plunger and spring to substitute — what are your thoughts (see below)? Has anyone gone through this or knows where to find the proper spindle spring and plunger?

CLICK HERE FOR IMAGE OF MARK I PARTS AND SHOTGUN PARTS

Why would those not work? You might have to fit them to make them operate perfectly but I've made small parts like that on a lathe. Why would this be different? I doubt you'll find originals.