Custom Android Firmware Rom for MediaTek 6582 Chipset MTK Rom Porting SP-Flashtool

General information for the business: We sell Android phones
Description of requirements/functionality: I sell some phones with MediaTek 6582 chipset, they currently have Android 4.4 version on them, I have the firmware files that I am able to flash with SP-Flash Tools. Before I do this I make some customisations such as wallpaper and some build.prop changes then I flash to the phones.

I have noticed that the developer community has made Android 5.1 available for this chipset:

http://www.codeofmonkey.com/resurrection-remix-5-1-for-all-mtk6582-users/

There seems to be lots of guilds on how I can port this to my device but I have been unsuccessful in doing this as it relies on TWRP or CWM, I have failed at all my attempts to port the rom over.

I just need someone who can build a stable rom based on Android 5.1, you can build one yourself or port one of the existing ones available. You will need to provide the rom in SP-Flash Tools format so that I can flash to the phones myself.

Of course I can provide the Android 4.4 firmware rom for you to work from. Below is the link. It is SP-Flash Tools firmware

https://drive.google.com/file/d/0B1DWZmzov0w0YjNkenNzNXZMSFk/view?usp=sharing

I must stress the final rom must be stable as it is going to be put on a consumer product to be sold.

Look forward to working with you.
Specific technologies required: Android
OS requirements: Windows, Linux
Extra notes: