Ryan Tafazolli headed the visitors into a 35th minute lead, only for Lamin Colley to equalise for the Pilgrims 16 minutes after the break.
The match, watched by a crowd of 920, was designated in honour of Blackwell, who stepped down from his long-serving secretarial role at The Jakemans Stadium in May.
Boston (4-3-3): Christian Dibble; Kalern Thomas (Jake Williams 46), Joe Maguire, Nat Brown (Josh Green 31, Cameron Johnson 73), Courtney Wildin; Joe Burgess (Lewis Hilliard 48), Herve Pepe-Ngoma, Grant Roberts (Malachi Lavelle-Moore 46); Marcus Marshall (Jay Rollins 46), Waide Fairhurst (Lamin Colley 46), Jason St Juste (Callum Chippendale 46). Subs (not used): Liam Adams, Andrew Ofosu, Jordan Linley, Michael Emery (gk).
Referee: Kevin Friend.
Attendance: 920 (275 visitors).