Ls swap into 1998 4.3 5spd 1500

I have a 1998 single cab with the 4.3 v6 and a 5spd nv3500 I believe... I want to swap in a 5.7 or 6.0 and keep the truck standard.
A little bit about the purpose of the truck: to be a daily driver (60 mile round trip) and to eventually run a 12 second 1/4 n/a and then a 10 or lower after boost..
. My first question is will the nv3500 be strong enough for a while until I can replace it with an nv4500? Or is there a better transmission?
I am also planning on purchasing a complete take out, which will most likely come with a 4l60e , can the ECM be used for a manual, ? Also what are these transmissions worth used ?
So far I am taking into consideration I will need the following for the swap. , please let me know what I'm missing
Motor mounts
Radiator
Electric fan setup
V8 fuel lines ?
Bell housing?

there's a whole section that covers OBS LS swaps.
but the stock 5 speed will be fine. the LS PCM can be tuned with or without transmission shift tables. if you're trying to race it, the 4500 is a bad option - yeah it's stronger, but the gearing sucks for racing & the clutch for either ain't that good for shifting fast or high in the RPMs. if you're 2wd, look into a T56 swap from a GTO (preferably) or a Camaro/TransAm

Thank you very much zebra!

Is there any bell housing difference for the t56 or will it match right up

Also, if I choose to keep my 3500 on for now would there be any bell housing change or any other difference?

Get a 98+ t56 transmission with a good clutch. The nv3500 doesn't like to shift past 3.5-4k rpm let alone 6-7k rpm.

i've shifted mine at 5500


...it wasn't the best feeling in the world, but it did it. that was also only for the first few times after a clutch fluid ranger flush. after that, you gotta double-clutch it - but that's more because of the hydraulics

as for bolting up, the nv3500 is a one-piece unit (the bellhousing is built in), and any SBC/BBC/LS engine can bolt to any RWD GM transmission

Thanks very much guys, my 4.3 has developed a knock haven't had time to investigate but it sounds like a connecting rod on cylinder 6.... So I may have to slap another 4.3 in for now .... I'm thinking I can get it done for about $1000.... How far off is $1000 from getting an ls swapped in and driving with maybe some detail to work on?

depending on the engine you find, you're most of the way there.

As Zebra stated, it depends on what engine you find and for how much.

After a trans fire burned up most of my wiring harness along with cooking the trans, I decided to go the LS swap route than finding another trans to back up the old tired 350 Gen 1 small block. My engine was also developing a rod knock so this seemed the best route. After scouring Craigslist, I scored a '99 6.0 with all the harness/PCM along with another transmission for $750. I sold the old engine for $150 and the burnt trans for $50. I bought a new radiator, engine mounts and other incidentals and still wound up spending just under $1000. If you have the time to shop, the deals are out there.