  We supplement \ML methods with a \MC simulation to re-investigate the SN1987A
neutrino burst detection by the IMB and Kamiokande experiments. The detector
simulations include background in the the latter and ``dead-time'' in the
former. We consider simple neutrinosphere cooling models, explored previously
in the literature, to explore the case for or against neutrino vacuum mixing
and massive neutrinos. In the former case, involving kinematically irrelevant
masses, we find that the full range of vacuum mixing angles, $0 \le \svac \le
1$, is permitted, and the \ML mixing angle is $\svac = .45.$ In the latter case
we find that the inclusion of ``dead-time'' reduces previous $\mnue$ upper
bounds by 10\%, and supplementing the \ML analysis with a \MC goodness-of-fit
test results in a further 15\% reduction in the $\mnue$ upper limit. Our 95\%
C.L. upper limit for $\mnue$ is 19.6eV, while the best fit value is $\sim$ 0eV.
