Still air take-off distances increase at about 5-6% per 1000' of D.A. for a normally aspirated engine or 3-4% for a turbo-normalised one.
Establishing your sea-level datum will depend on the propeller type (FP or CS), power output and prop efficiency, so difficult to generalise. If your configuration and weight is similar to the Van's example then their distance should be fairly close.
Some approximate rules of thumb:
Headwinds and tailwinds: Divide by take off safety speed, subtract from 1 for headwinds, add to 1 for tailwinds, square that number for TOD /LD factor
Weight - adjust by weight squared for take-off, but linearly for landing distance (i.e 10% weight increase= 20% on TOD and 10% on LD
Density altitude - 6% per 1000' for TOD, 4% per 1000' for LD
Gradient - 5% per 1% gradient for TOD and LD
Snow, long grass, standing water etc. add lots or stay at home