Ross
I looked at horizontal boring, but it presented problems. I first looked at using the overarm to support the outer end of the boring bar. Due to work features in the way, the bare length of boring bar would have needed to be nearly double the length of the whole engine, and my overarm, long as it is, would still have been too short. Even using a cantilevered bar like I did, the work would have had to overhand the front of the tilting table in order to be able to back the boring bar out of the hole. I don't have those fancy T-slotted parallels like you can borrow from your Berco to support overhung work. I suppose I could have used the big fixed table that I have, but it has a bit of droop* and is a hassle to install.
The vertical method worked a treat, as you see. The Z travel is long and gave plenty of clearance to back the bar out of the hole to take a measurement. The method also had the advantage of allowing the chips to just fall out of the hole, so no issues with chip clearance.
Rich
*Not that droop would matter much. Unless I shimmed the base, it would result in a tiny amount of "desaxe," or the cylinder axis not quite parallel to the base bottom. I am using the base bottom as a reference surface, and even scraped it to good bearing before I started machining.