Is a carbureted 5.3 swap with a 700R4 a good idea?

It's a simple, proven combination — no ECM harness and no transmission computer.

What carbing an LS takes (Speedway):

• Carb intake: single- or dual-plane, from about $279. For the street, a dual-plane (roughly 1,500–6,000 rpm) gives the best bottom end and mid-range.
• Ignition controller: every LS is distributorless, so you need an LS ignition box to fire the coils. Boxes like MSD's LS unit use the factory crank and cam sensors and come with basic timing curves preloaded; a laptop is optional for fine-tuning.
• Fuel: no mechanical pump option on an LS, but you don't need 58 psi. A low-pressure electric pump that flows 80–130 GPH at about 7 psi needs no regulator or return line. An inline pump must sit below the bottom of the tank.
• AFM engines: replace the cylinder-deactivation lifters with static lifters for any carbureted build.
• Throttle linkage: the stock linkage may work with the right adapter, or use an aftermarket cable.
• Gauges: you'll need sensors that match your gauges.

The 700R4 side: it's hydraulically controlled with a TV cable, so it pairs naturally with a carb. The TV cable must be adjusted correctly — Speedway warns that if it's out of adjustment even a little, the transmission may shift too fast and burn up the clutches. On an LS you also need a dished flexplate with the 10.75 in converter pattern and a converter sleeve, because the LS crank sits about 0.400 in shorter.

Trade-offs: Speedway says EFI beats a carb for drivability, cold starts and consistency, while a carb makes great peak power and gets you home when something's off. For a simple, classic-looking cruiser, carb + 700R4 suits the job.