Can power heads be swapped?

Have a '93 115hp evinrude v4 crossflow. Have serial# but not with me now that's locked up. Question is I have a 1977 85 hp. Javelin Serial # j4766810. Model 85ETLR77S. That has compression at 125, 120,115 an 112. Trying to help out a friend's grandson on first boat. Is it possible to take '77 powerhead and put on '93 ? Is powerhead gasket the same? Is driveshaft splines the same? If I take stator, trigger off '93 will it work on '77 with '93 flywheel ? And get rid of '77 switch box and go with '93 cdi box and coils. Note
'77 bosses don't have threaded holes for coils. Were '77 has bracket that mounts on top for coils.
Thanks for any info.

There may be issues with slight difference in fit of the driveshaft.----And the gasket between the block and exhaust housing is different.------So it is a NO GO here.