318 lA Rocker arm stamping and orientation questions

Hi guys, I am ready to re-install my 318 LA engine into my 65 Barracuda. Here is an image of the block stamping.
View attachment 1715448233
When I took apart my engine and ran the numbers, the engine was re-built using 273 heads and stock intake. Since I am using a new Edelbrock Performer intake, I sought out some new, matching 318 heads. Pictured
View attachment 1715448237
Re-installed the lifters in their original correct sequence. Took out my rocker arms and did some test fitting. I noticed that the rocker arms are stamped and not shaped the same way. I thought that I kept my rocker arms on their shaft in the position that they came off the car, but maybe not. Looking at the stampings, I see RH and LH stampings as well as the pushrod pocket being off-centered in some of the rockers. I have RH and L stampings mixed up on the rocker shaft right now. Can someone help me with the proper sequence of the rocker arms and the left hand/right hand orientation? Also, I noticed that the rocker shaft is held away from it's receiving location on the heads....I assume that the valve springs will become compressed as I tighten the rocker shaft into position. Thanks in advance...
View attachment 1715448260
You say your old heads were 273's. Are you running a hydraulic cam and did the old heads have adjustable rocker arms?