Photoshop :: How To Join Template And Picture Correctly?

I do book cover design use action script. There is basic PSD template, which has high resolution 300dpi and large image dimens. 2200 x 1450). I should insert a picture which has much lower resolution 96dpi and smaller size 430 x 640 pix. I need that this picture covered full area, i.e. had the same size as a front cover (at least same height). If I just copy and paste this picture it have very small size due different resolution and dimensions. If I just lower the resolution and dimensions of a PSD template to correspond my picture, this gives error when action script run (in Step2), and also it is inconvenient to work with small template. How to join template and picture correctly?