With a block altitude clearance, what you COULD do is to follow the FMC recommended level as it changes by 100ft. Once it recommends 100ft above, you could set the MCP 100ft higher, press the MCP Alt switch to set the new cruise level, and climb.
By doing so, you will remain in VNAV, and because the change in level is only 100ft, the aircraft remains "captured" and so the engines don't go up full power.
AP stays in the cruise modes.