Just an update, I was not able to run ReactOS on my working hardware due to atom or celeron issues.
What I did Note was that earlier versions of ReactOS included “SmartPDF” which was supposedly a variant of the earlier Poppler based SumatraPDF, however that was dropped from ReactOS in May 2008.
Many users have said in the forums they could run SumatraPDF without too many problems from 2007 up to the 2016 x32 version 3.1.2 so I would be testing that first.
Most ReactOS bug reports for SumatraPDF are “resolved/wont fix” there is only the odd open one for fullscreen mode where SumatraPDF is not fixed as "OnTop of the toolbar. However that can also be seen in Windows 10 with current release, where “Always on Top” apps or the Toolbar are allowed to override SumatraPDF.
ReactOS x64 is Bleeding Edge Alpha Alpha so dont expect SumatraPDF 3.2.# x64 to be supported by ReactOS for possibly some time.
It would be beneficial if someone running newest versions of ReactOS could test a current SumatraPDF Pre-Release x32 build and report their findings.
This list https://reactos.org/wiki/User:Matthiasbasler#Office is now out of date but reports 3.1.1 ran well. The current recommended Rapps version is 3.1.2 as downloaded by https://github.com/reactos/rapps-db/blob/master/sumatrapdf.txt