Let me play devil's advocate a smidgen...
You would have to careful not to place too much credence in relief of symptomotology by SL nitro in this case. On the chest pain differential is also esophogeal spasm, which she has every reason to potentially have as well AND SL nitro will relieve pain from esophogeal spasm. Of course, a goose in spasm is not likely to cause EKG changes not + enzymes. But, it takes a while even for our most senstive enzyme assays to turn positive. Furthermore, approx 25% of active ischemia patients will have a normal EKG.
Now - with a perf'd duodenum...a fresh perf in a younger, healthy pt - maybe sit a spell & be OK, but with that pt population, it would be very rare to be having to cope with her co-morbidities. Being as she old, frail & has been sitting on her perf, I think she needs bright lights & cold steel ASAP...assuming you can get the active ischemia to lax up.
I totally agree with lining her out prior to induction (9Fr IJ & an a-line). And, before starting beta-blockers, dump a liter of LR in her.
Regarding cooling out the ischemia & stabilizing hemodynamics - I agree w/ NTG & neo gtts, but I would have used esmolol for my beta-blocker gtt - much more rapid response to titration. If her BP took a dump after the metoprolol, you are in for much longer lasting hypotensive ride whereas you could just turn off the esmolol & your out of the woods in a couple of minutes...hopefully.
I disagree w/ the eVOMIdate induction. Hell, she's acting like a heart w/ known & active disease; so treat her like a heart. Plus, it's not like she gonna be d/c'd home from same day. I would do a benzo/opiate induction just like I would for a CABG or valve. Take her down nice & easy with midazolam & fentanyl. Frail old lady shouldn't take more than 5~7mg midaz & 10~15ml fentanyl. Plus, she'll be cozy & comfy on the blower all the way to the ICU where she can chill overnight. You know damned good & well from your description she's gonna spend some time in the ICU on a vent. Were she younger &/or with fewer co-morbids - she might be extubated post-op, but in her case, I seriously doubt it.