Replacing A/C wall unit with window?

Want to replace an A/C unit that is in a wall with a window. The outside of the house has vinyl siding on it. The A/C is trimmed with j-channel around it. After the A/C unit is removed, thinking of removing the siding and purchasing a window with the flanges around it and installing it as a “new” installation. To prevent water penetration might put rubber tape over the flanges followed by the j channel to trim out the unit. One question I have is this the proper way to flash the window to prevent leaks? Also, it seems like alot of work to remove the siding to be able to have access to nail, seal and put the j-channel around. Is there an alternative to this method? Thanks for any suggestions.