273 adjustable rockers on 360, very little oil to springs

Yes for sure check the rocker installation. The rockers have a notch on one end of the shafts. the Notches should be down and to the left as you look at each side of the engine. This aligns the 1 enlarged rocker bolt hole on the underside of the shaft over the rocker pedestal through which the oil flows into the shafts. (2nd pedestal from the left on each side.)

Oil on the springs may helps spring cooling but IMHO is not all that necessary unless you are running extended high RPM's like in circle track racing. And the mechanism for 'throwing oil' is not really there; there is no 'cup' like for stamped rockers. Questoin: Are you getting oil on the tips of the valves, under the rockers?

The biggest thing for the 273 rockers is the pushrod cups; the oil HAS to be getting through the small hole in the adjuster side of the rockers so that it can then flow down around the adjuster and into the pushrod cups. Some of the shafts have a set of small holes on that side to insure better flow to the adjuster area. I would pull the covers and look to see that there is a lot of oil around the pushrod cups.

BTW, on your Mobil 1 (which I run in a lot of engines), are you running any any additives for ZDDP? The current crop of 10W30 oils for the street, marked for 'SN' service, don't have the levels of ZDDP that is considered adequate for cams with higher spring pressures.

Check out this chart; it shows all of the 10W30 Mobil 1 grades to have 900 PPM of zinc; your oil should be at 1200 or more for flat tappets with aftermarket springs.
https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide.pdf