Using both MP light springs will let it start advancing at ~600 RPM, way too low in most apps. I would take both of em out & sub in both of the OE springs from one of your parts dists then set your initial with the "vacuum gauge method" then with that math figure in hand shorten the slots to get 35 total (SB) & 36 to 38 total (BB) with vac adv disconnected/plugged then adjust the springs then hookup/adjust the vac adv & the procedure for the springs and vac adv is too long to type out again when it's there in the search function somewhere I just dont have any luck with the search function. then tossing the heavy spring with the elongated loop on one end & subbing back in ONE of your MP light springs & keeping the OE light spring will be a good start. Not sure why there's no new MP dist available except that they might be on back order but imnho you dont need one, you're set with what you have.