Gradius: Comeuppance (Level Hacking)

[RhysOwens101]

This is gonna be a Gradius 1 NES Hack that will be made off the Arcade Conversion Patch (http://www.romhacking.net/hacks/1573/)

The hack is going to be a prequel to the original. You will play as a prototype version of Big Core that was originally put away by the Bacterians.
As of now, the only thing I have changed is the sprites and text on the title screen, and I don't know how to or can't do (so need help with) what's below.

What To Do/Learn To Do:

• A Proper Plot
• New Levels (This is to be done first)
• New Enemies
• More Bosses
• Change the Laser to a single shot that can be upgraded to fire up to 4 shots in a pattern just like the Big Core boss's
• Change the Shield to a Force Field (Like in the sequels)

Utilities Used:
FCEUX (Hex Editing and Debugging)
YY-CHR (Graphics)

Screenshots:

[Spooniest]

Vic Viper changed to another sprite? I'm not really familiar with Gradius jargon.

[RhysOwens101]

Vic Viper changed to another sprite? I'm not really familiar with Gradius jargon.

What do you mean by Jargon?

[Midna]

Vic Viper changed to another sprite? I'm not really familiar with Gradius jargon.

The Big Core is the primary boss enemy in the original Gradius.

[RhysOwens101]

The Big Core is the primary boss enemy in the original Gradius.

Mmmhmm, appearing in nearly every game in the series in over 5 variations.

[RhysOwens101]

Update: I would love to do coding, but I can only do graphics or text because they are the easiest to do but I don't want many graphical changes because it's set before the events of the first game.
This is why I need your guys' help to find the offsets of the level tiles because that's what I want to change first. Definitely an un-documented game.