Which is better and why? Old 440 or newer 6.4?

[69Charger#2]

Kind of a situation-specific question. I have been away for a very long time. Life got in the way and my Coronet has been sitting dormant with the engine in pieces. I want to do something with it, but I just don't have the time, so I'm thinking of farming it out. Anyway, in short, it is an R/T with a period-correct 440, but not numbers matching and not the hi-po version that should be in there. I had bought a bunch of parts for it, such as the edelbrock intake, carb, cams, and valve springs. The big question, though, should I continue down this path and have the 440 finished as is? Should it be rebuild from the bottom up with the goal of 450-500hp? Or should I go with a crate 6.4? There are so many things to take into consideration, but I think the biggest one for me would be: which would be more desirable? Since it isn't numbers matching anyway, originality is kind of out the window. But would the car be worth more with a period-correct big block that has been resto-modded or with a reliable and possibly higher-powered and fuel injected modern engine?

So that's the big topic. Smaller topics:
1. Anybody know a good place in or near NJ for this work? I have reached out to 5 or 6 places and only 1 person replied (more on this below).
2. I'm a little confused about the transmission issue. Will the BB 727 mate with a 6.4 crate? I have found SB plates, but nothing yet on BB. I know the 6.4 is a SB, so I guess the question is if there is a plate to convert the BB trans to a SB? Or can the bell housings be swapped??

On the whole "someone to do the work," I think I'm scaring them off. I just have NO IDEA what this work costs. The one who responded said "I won't give an estimate through email. I have to see it." Ok, it doesn't run and is in boxes, so how the hell am I supposed to do that? I even broke it down to, what I thought, was a simple ask. I said "how much to remove the 440, rebuild it to 450-500hp, and reinstall it?" He still said "I have to see it." Maybe I'm crazy, but I would think that should be something that could be estimated. Obviously, if the block is cracked, that changes things, but just say that. "If ..... then .... $xxxxx." I mean, what do folks do? Trailer the car to them, drop it off, and give a blank check? OK, I'm sure some do. Like I said in my emails to them, I just need to know if we're talking $10k or $100k.

I faced the same situation with my numbers-matching 383/Auto. Body and interior had been restored, but engine was tired (104k if the odometer is accurate). I went the 440 route - bought an early 70's block from a Mopar friend and found an engine builder in the area. I just got the engine back last week. Complete engine build, with the block cleaned, milled and bored and all new parts. Aluminum heads and a lot of polished and dress-up parts were used, as I went for looks and not for high horsepower. Since pandemic, parts are expensive and it took a long time to get them; over a year to complete the build. (This is my first and only experience with an engine shop, so I'm not sure if this is typical.) Engine dyno'd at 519 HP/575 torque. I will have over $30K in the engine. (I was not able to get an estimate before the work was done, either.) To me the 440 looks "right" under the hood, whereas the 6.4 seems out of place. Both my Mopar friend (60-ish) and my engine installer (late 20's) thought this was the way to go, in keeping with the character of the car. I also prefer to keep the car more period-correct, although I am replacing the 727 with a Tremec 5-speed.
That said, I met a guy with a '69 Charger who went the 6.4 route and he is really happy with it. Modern reliability, and probably less $. He went more the restomod route with replacement instrument panel and updated interior. He also went with the Tremec 5-speed for the transmission.
Pluses and minuses both ways. Which ever way you go, make sure you are dealing with a shop with integrity. Best wishes.