I have a 440 im assembling. My first build. Its a solid cam, with iron adjustable rockers. Ive never done this before so im not sure if this looks right... Everything was checked with lifters off the cam center and 0 lash

From the 2 adjusted end pushrods it appears your pushrods are too short as ideally you want ~1&1/2 threads showing underneath when you're on the base circle & zero clearance plus the added amount of gap (lash) for your particular solid cam (& cold breakin lash may be slightly different + or - than hot running lash, check with your cam mfgr). No opinion if that amount of extra threads showing will be an issue but I'd be inclined to think not but others will chime in. EDIT you mentioned 0 lash so be sure to add in the breakin lash clearance recommended which will shorten the # of threads showing underneath

ive heard 2 thread is the rule of thumb. Im at 3. Both the deck and heads have been resurfaced so I figured they would be just a tick under but in the range.

3 shouldn't be a problem, it just looked like ALOT in the pic & when you unscrew em to add in the lash you'll be right on the money.

Every rocker arm manufacturer has their owned preferences, your rockers look like they are Crane Ductile iron rockers,if so call them and ask how many threads they want exposed under the rocker arms I like to see 1 to 3 threads exposed max on ductile iron rockers, if you are going to replace them shoot for 1 1/2 threads exposed with the lash Most stock 3/8 diameter adjusters I've found on ductile iron rocker arms are 24 threads per inch If so that is right at .042 per full thread