I believe @oldsmobile joe has at least one LT1 swapped G Body.
did someone say my name?
yes, i have done three lt1 swaps, my first in a 66 belair. and two gbodies with a third one planned.
the easiest swap is a carbed sbc, followed by an lt1 and then the ls swap. i have no experience of the sbc vortec engine swap and am confident others on the forum will pipe in concerning this swap.
if interested in the lt1 swap, then try and get the whole car. when i did my caballero (el camino) i used the following from a caprice or roadmaster.
motor and trans, because my first swap was based on the 95 roadmaster, i have stuck with those years or converted to that year. i'll explain, even though all B body cars used the lt1 between 94 and 96, there are minor changes between the years. the biggist being the transmission. 94 4l60e torque converter used a standard on/off lockup for the torque converter. 95 used a pulse width modulated lock up torque converter. and 96, while still used the pulse width modulated torque converter, it changed components internally. so over the three years, there was three different trans requiring a matching ecm. for the engine, there were two big changes that started in 96, gm added an external crank sensor to monitor for misfires, and they added two more o2 sensors to monitor the cat converters. these changes were mandated by the feds to start in 96.
entire engine bay wiring harness, while not all of it is used, its included with the purchase(free) and is useful
entire dash/interior wiring harness, while most of it is not used, it provides you with the diagnostic scan tool connector, pass key(if used), cruise control wiring, and other wires for brake, dash sensor, fuel pump wiring, etc.
all the fuel lines and emission lines from the engine bay to the fuel tank. i was able to use all of this, no modifications, direct bolt in because i used a wagon fuel tank with a sedan filler neck attached. mounted the fuel filter in a similiar position as the B body. even used the charcoal canister.
because you have a el camino, grab a fuel tank from a B body WAGON. wagon tanks fill from the side like the el camino and will install with new Bbody tank straps.
for the cooling system i have done it several different ways. one way is with the radiator, dual cooling fans, lower and upper radiator hose from a lt1 F body. some fabricating skills required. other way is to use the gbody radiator. Bbody lower radiator hose and F body upper radiator hoses will require splicing to gbody hoses. i used this second route on my cutlass wagon along with the Bbody tow package clutch fan option.
exhaust is up to you, lt1 cast iron manifolds fit with no issues. Bbody manifolds will require custom exhaust fabrication. none of the down pipes will fit.
if you come across F body cast iron manifolds, they fit also, and the Ffody Y pipe fits with no modification. i went this route, didn't need a double hump trans cross member and a single exhaust outlet is cheaper than a dual exhaust system. i, like gm, don't like having a hot exhaust pipe under my fuel filler tube.
shifter, if money is tight, you can use the Bbody steering column. with modification it will fit. yea i know, its a column shifter but this will provide you with the correct shifter quandrant for a 4 speed auto and it allows you to use the factory pass key ignition cylinder.
rear end gears, up to you, i'm running a 2.73 gear on both gbodies. these are street driven cars and are built to daily driver standards. meaning i can and have jumped in one of these and know i can drive it 8 hours straight with no worries
this is just the highlights of my lt1 swap. this is the way i did it. there are other ways also.
i see your new to the site, i know nothing about your mechanical skills or knowledge. keep asking questions and we'll keep providing answers or options for you