I think all your questions can be answered in the posts which Hogan generously searched for you. 4130 has been practically beat to death on here, time and again.
All I can really share are my personal experiences with 4130. There are some tricks to attaining acceptable welds with this critter. The number one point is preheat; almost without variance on parts that are thicker than 1/4", you have to apply some level of preheat to this material. If I am welding sheet or thin-wall tubes, I use a torch and get it to a good 350 deg. F. or so. Second is to control the post-weld cool down. This is especially important if you are going to be doing any sort of PWHT, except maybe for a straight up stress relief. For fillers, ER4130 seems to do well in a wide range of applications. I am not sure, but by the stated thickness of your parts I would guess you'll be using a higher deposition process than GTAW, so for filler I can't really help you out there. If your weldments are not being heat treated, an 80s or 90s filler works well. I have done pipe in SMAW with 8018 with no problems.
Good luck.
Here's my best guess. Since you have a lifting appliance, you want to match base material tensile as closely as possible. Use a good 100Ksi filler. I don't understand the RHC of 29+, you want toughness and ductility in a lifting device as well as ultimate tensile, but what you got is what you got. Preheat to 350-400F, don't go above 650 interpass. Get it into the furnace while still hot if possible, slow cooling otherwise. Do a post weld stress relief at about 75 less than the temper temperature for two hours minimum, three max. This will relax the stresses and should give you a weld with around 90Ksi ultimate tensile, good ductility and and notch toughness. I'm assuming that the 58K pull test indicates a MWL of around 38K, so if you develop 90 Ksi in the weld, you have a good chance of staying below the fatigue limit during operation of the lifting eye.
edited RHC number and cooling info
By tom cooper 
Date 04-01-2009 16:22
Edited 04-02-2009 12:08
Our shop works w/4130 routinely. I have seen several odd instances myself where the specs call for material already Q&T'ed to some very high value prior to weld. So what do you do after? You only have three post weld options:
Option 1. restore full strength AND tougness by a post weld Q&T operation. In this case you need to use matching 4130 filler. You would be better to weld normalized material and Q&T the entire weldment afterwards. You will naturally complete all precision machining afterwards as well.
Option 2. typical stress relief. In this case you need to keep your SR temperature 50-100 deg below the tempering temperature which was probably ~1050-1100 deg F, so your SR will be in the neiborhood of 950 deg F. You can use a 12018 rod and you might find 140xx somewhere but the manufacturers may well tell you that these are intended to be used in as-welded condition. If you post weld SR then you will degrade the weld metal strength somewhat. In either case your weldment will never have the full strength of the Q&T base material that you started with. On the other hand, you will have conditioned the HAZ which is very important with this alloy. It is a trade-off to be made by your customer, be sure they understand this.
Option 3. no stress relief. This is not really an option for 4130 but if as-welded is acceptable to your customer, you again will not match the strength of the Q&T base material that you started with and you will definitely lose toughness in the HAZ. Make sure your customer understands this. If this is your circumstance, please use a very high preheat of 400-500 deg F. PLEASE DO NOT EMPLOY AS-WELDED 4130 IN A CRITICAL LIFTING APPLICATION unless you x-ray (or UT) the final weld and even then it is a stupid idea.
In any instance I can think of, by Code or by spec, you will need to qualify a procedure that demonstrates the post weld operation that your customer demands.
