1973 340, want more power.

A discussion of how to get there and meet the 450 HP goal will follow (I am sure), and will involve pistons, heads, combustion chambers, etc. I know you may just want a list of parts; you might get that. But this is one thought process laid out if you want to understand how you are getting there.

If it's 99% street, then you will be happier (I am fairly sure) with an engine that does not need to be revved way high to just get moving. So maintaining a decent low end torque curve would be a good objective. Whatever mods you do, make sure it does not sacrifice too much of what is called DCR - dynamic compression ratio. A DCR in the low 8's or high 7's will keep torque up but still allow you to run pump premium up your way. Discussing/computing the DCR for various piston, combustion chamber, and cam choices as you go along can be part of this thread.

With the lower compression ratios that came in the '73 340, then pistons should be on the list to select to get the DCR (and static CR, or SCR).

Then head breathing capacity to get to the 450 HP mark. Look at the below linked site for some head flow info; you will be targeting something a bit more than the unmodified port flows of Edelbrock RPM Performer LA heads. There are a few ways to get to these numbers. #1---Head Flow Charts & Comparisons

Then cam selection will need to match that and allow the head flow to work for that HP level. If you want to keep a broader torque curve (for street use), then getting a cam with a high lift to duration ratio will help, and not going wild on duration. Roller cams also allow better lift to duration ratios, as does using 1.6:1 ratio rockers.

Then an intake, carb and headers to match; those selections are fairly easy.

Your budget is realistic IMHO.

And just know that a normally aspirated, carbed small block will not have the same broad torque curve of that FI 6.4L SRT engine. There are some major differences in fuel delivery and air delivery between the 2 engine types that result in some big differences in behavior. So it won't be exactly the same. But it WILL be fun!