http://www.stone-circles.org.uk/bypass.jpg
The google map shows what looks like several barrows to the south of the river and I've added a dashed line round where the cemetery might be but nothing shows up at the grid ref given in the report for the north side of the river so I've no idea how big the cemetery might be on that side. The road overlay of 'Route Z' on the bottom image shows that it cuts through the southern cemetery but the image is my best guess estimate (ie it's not official).
As for interested parties have you tried the following, they may have been consulted or may have further information?
- Witham Valley Archaeology Research Committee
c/o Heritage Trust of Lincolnshire
The Old School
Cameron Street
Heckington
Sleaford
Lincolnshire
NG34 9RW
or I think you might be able to reach them via this page-
http://www.lincsheritage.org/info/contact.php
-Washingborough Archaeology Group
http://www.thelovens.co.uk/wag/index.html
Their website doesn't seem to have been updated recently so I don't know if they are still operating.
-Chris