Sorry I missed your last PM but I finally saw this one---my error.
AS for the pitot head, you probably need a pin vise---a hand held device that accommodates drill heads of various sizes and is used to drill small holes with a twisting motion as you hold the model. With a pin vise and the proper sized head, you should be able to drill out the hole to mount your after market pitot head---but do it slowly and with care. Once installed, with a bit of glue, a dab of paint and you are good to go.
Micro-Mark carries pin vises but I didn't see the one I usually use in their latest catalog. Of the ones shown, item# 21104 comes the closest.