The pink is due to the use of saltpetre not to under-cooking. This is very difficult to come by nowadays as it is used in home-made explosives. The last time I tried to buy my usual 1/2 ounce in the pharmacy which has supplied me in the past I was told that it is now illegal to sell it (in UK). Oddly, you can buy it by the kilo from Amazon. Weird!
The best recipes for anything in the charcuteries or English pie-making line is Jane Grigson's "Charcutery and English Pork Cookery". I expect you'll find a copy on Amazon. Or try this
Make the perfect Melton pork pie this Christmas | Great Food Club