Engine diagnosis help

As some of you may recall I purchased a cheap 944 turbo last fall for use in HPDE/autocross. I did my first event about a month ago with BMWCCA at Watkins Glen and had an absolute blast, but the car didn't hold up as well as I had hoped. The big issue is I lost a cylinder during my last session. It sounds like there's a box of rocks in the top end. The noise doesn't change load vs. no load, which combined with the fact that I perceive it as top end noise makes me think I didn't roast the #2 rod bearing (although that's the cylinder that is dead). It has always had a bad lifter noise on #2 if the engine is low on oil. I was guessing a broken valve spring but when I finally pulled the cam tower a couple days ago everything looks fine - the valve springs are all intact. There are 2 soft lifters, one each on #2 and #4, but nothing that looks obviously bad - no scoring or marks on the camshaft or valve stems. Of course, that doesn't mean that I haven't bent/broken a valve... I pulled the plugs and there wasn't any physical damage to them, just lots of oil on #2. It's been "normal" for this engine since I bought it for the plugs to be oily, but the ones that were firing had a uniform light grey color on them (probably from burning the oil on track).

The questions is, where do I go from here? I am considering a leakdown test but I don't have a leakdown tester or compressed air but I could either borrow a friend's pancake compressor or spend the $35 for the small one that HF has on sale along with the $40 for their leakdown tester. My other thought was to just pull the head, since I'm probably 80% of the way there - all that's left is dump the coolant, disconnect a couple of coolant lines/connections, unbolt and remove the head. I'd then need to invest in a head gasket set for ~$150 to put it all back together. Any other ideas on what to do to diagnose this issue?

I have indeed had a lifter noise turn out to be a rod bearing. BUT before I would go that far, I would pull the plug, take the piston to BDC, and insert a borescope through the spark plug hole and take a looksie.

For a bent valve, the height on the bent valve will be significantly lower then the others when compared.

I really expect to see a broken piston and/or ring for what you are describing.

Sounds like a good plan - do you have a cheap source for a borescope?

The Glen has long sweeping turns, and the #2 lifter was already making noises when low on oil; and you gots oil on the plug...pop off the head. I think Ranger 50's got it right. Break out the visa card....Know anyone who works at a hospital for the quickie look with a borescope? That or beg/deal/quiver your lip when talking to a tuning shop that'll take a quick look. Cheapest and best is to pop the head, and check out/measure everything. Personally, I'd be pulling the engine in prep to replace the rings, and HOPE it's just the rings.

You can bolt plexiglass to the block for a "ring past" test, once the block is off.

HF coupon for a $80 scope. But just one of those obeident deals with just an eyepiece and light will work.

Well, I got up this morning and decided to just pull the head. After a few hours this is what I found:

That explains why #2 wasn't firing, but not why it sounds like a can of marbles. There's no scoring to the cylinder walls and the missing piece wasn't in the cylinder. I'll pull the manifold off the head and take a peek but I have a sneaking suspicion that the missing piece is in the turbo :( I also drained the oil and there was nothing at all on the magnetic drain plug so I'm assuming that is a good sign that I didn't spin a bearing.

Next question - just pull and replace the valve myself at home, or take it to a machine shop to check the head and valve seat? 951 heads are supposed to have ceramic exhaust valve seats. Curiously, that head has a part number that starts with 944 so I'll have to do some checking to see if it's a turbo head.