Rule of thumb: don't touch arcs. It makes gat/flak no longer viable for pubs. It hurts new players and limits gun choices without affecting balance. More unique ships become nonviable while metas remain unchanged, or creates a new meta
A 60% buff to vert accel is excessive. For reference, squid vert accel is 4 m/s2, and this gives spire by far the best vertical in the game (all ships have the same top vert speed). I thought a buffed balloon and hydro made you shoot up like a rocket before, but now you don't even need a buff. Spire can already outmaneuver most ships in close range, less it's awkward profile, but now it's much easier to dodge and juke ships, if it wasn't already easy enough before. Top speed nerf is fine. 900 HP is huge, a 225% increase, and more than a galleon (800). Now you buff the hull and maybe even bring up another engi when necessary, whereas before you rarely buffed hull and almost never had another engi on hull
Previously, the spire was weak to kill and disable, now it's only weak to disable. In short, reduce the severity of the changes. If it needs more vert accel, buff it 10-20%. If it needs less hull and more armor, nerf 20% buff 30%, or anything but 50+%, which is overly excessive. Small but important changes have big effects. Top speed nerf is good but do not touch the arcs