If you run the blower as they come from the manufacturer and don't have any plans for further increases it's hard to beat the motor warranty that eforce or eldelbrock offers. There claims are on the money 580 to the wheels with there can tune on a dynojet or 553 on a mustang dyno the torque was the most of the blowers aswell especially the centrifugal. They got a bad wrap on the LS3 but the LT1 is different story.. everyone is talking about the IAT'S and I know why.. it took about 3 mos. to get the air or pockets of air out of the blowers heatexchanger/ intercooler system. If I would of jacked up the nose got the small fill tune to the highest point it could of bypassed the time.
Reguardless of what you chose the fuel system won't do much more than where all the kits are you will need band aides like meth to lower temps or raise octane to increase power..
A cam shaft change will be required to increase the fuel lobe since the high side is driven off it. Probably a 4k part and labor task then through in another 1500 for lt4 pump and injectors.. now yout in it so take the heads off and knock the compression back to 10:1 or so.. this is pricey job since the motor has to be pulled unlike the ls3 where you can get the timing cover and oil pan off thanks to silicon and gaskets the LT1 is all tight clearanced and use high temp rtv to seal it.. so to do it right pull the motor..
I haven't noticed high iats like I did in the LS3 I could feel the hp loss once the temps got up.. in the LT1 I can't hardly feel any loss at all.. the shop made 3 passes no cool downs with idle and computer tweaks.. all passes on the mustang where 551 to 553 rwhp.. if that been my old ls3 it been 620 on cold pass then probably 525 once it got hot..
Here is a ZL1 with no cam mods running half 93 and half e85 maybe e77 or abouts, smaller pulley, and 1 3/4 headers vs eforce on 93 and tiny Borla 1 5/8 headers.. Zl1 2nd gear.. SS 3rd gear. Pretty close pulls but wife was driving .. He dynoed 630 w e85 and we dynoed 570 on the same dyno on 93.. if he was on 93 she would of had him I think he did 570 something aswell on 93.
https://youtu.be/bruKdOcKHAc
There all good choices.. if you going all out later on I'd get a AGP turbo kit or custom turbo kit. That was the best decision I ever made on my 5tg gen.. sitting at 746 to the wheels on 93 with no band aides! (Meth)