This is probably not something you can string together in your garage. You would probably be better served to find a wrecked Charger/Chrysler or some other vehicle with the 5.7 engine and grab the computers and the wiring harness. There will be many issues with a bunch of sensors that are not present on your '69. The 5.7 is rated at 350hp, not much of an improvement in power over a T-Code 440. 5.7 also had valve train issues on the earlier variants, so try to avoid those engines. If you are serious about the V-10 viper engine, they are expensive and hard to come by with a lot more computer and sensor issues.
A guy on FTO, also a FABO member, got a chassis from an SRT10, and swapped everything over to his Sweptside. I'll see if I can dig it up, I thought he had the engine running. But keep in mind, it was basically a custom build to fit it all together. Lots of work.
If your goal is a powerful C-body, a well-built 500-550hp bigblock stroker will be far cheaper, simpler, easier to build, etc.
If your goal is a modern EFI engine, a 5.7 would be much simpler than the 488, and 6.1 or 6.4 would offer more power in the same envelope.
If you're after bragging rights of an oddball drivetrain, be aware that many of those ambitious projects result in an unfinished car sold at a major loss.
The 488 is longer, so harder to fit, and you need to change to a Viper-compatible transmission also (it shares the bell pattern with the Cummins). Which means either fitting a 6-speed (major tunnel reconstruction plus conversion to 3-pedal), a 518OD (mild reconstruction) or finding a Cummins 727 (do they exist?) and tweaking it to perform nicely with a high-rev gas engine instead of a low-rpm diesel.
Plus all the ECU stuff, which will be harder to figure out than the G3 hemi stuff.
They just did this (or was it a repeat?) on one of the ass monkey car building shows on Motor Trend TV with a 60'ish Chrysler 300 and a Gen 1 Viper.
You may want to rewind the tape, or you may not as the engine didn't fit too well and firewall and tunnel had to be cut out and re-fabricated, yada, yada, yada, par for the course with those shows.
They went to some exclusive Viper only wreaking yard that had over 400 engines in stock or sold, (I can't remember) I lost interest quick as they kept switching over to some Model A rehab. Then there was the 'bagging' of the 300,